Picture of Yip Yip Costume
Whether you loved them as a kid or hated them for giving you nightmares, there's no denying it's fun to go around freely and anonymously shouting "yipyipyipyip" to those around you. Here's how to make a costume based off the Martian Yip Yip aliens from Sesame Street.

UPDATE: Some pics from WonderCon 09!

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Step 1: Materials

Picture of Materials
5-6 yds of Curly Fleece
I've found this fabric to work well for the body of the costume. It's soft, breathable, and light enough to move around in but with enough weight to hold the package together. The downside to curly fleece is it can shed quite a bit when it's fresh, so it gets rather messy. However, a good thing about this is that the fur on the fabric was so long that it easily hid the many safety pins I used. Another good option is something called Flurr (fleece + fur). You want about about 2.5-3x whatever your height is.

1-1.5 yds of Black Chiffon/Mesh
This is the mesh-like material that will form the mouth. It is important that the material be see-through, since this will be your window to the outside world. The mouth will probably consist of 2-6 layers of this material, depending on the specific fabric you have. The most important part is that if you hold it up to your face, you can see relatively clearly through to the other side (usually there is a light source outside of your costume), but no one can see into your costume through the mouth (no light source within your costume).

Contour Shaped Sponge
You can pick this up at your local Home Depot for a few dollars. A good half-oval shape is what you want. The dimensions I found were 7.5"x3.5"x2.5", and I eventually cut in half length-wise however. This will form the lip.

Styrofoam Spheres (x2)
For the eyeballs. 4" in diameter will do, or 5" if you want to go bigger.

This will be essential to keeping the costume on your head. Pick out something that is light, nothing too thick. You don't want to start sweating too much while wearing the costume. It should have enough structure to it though stay firm and not flop around.

Pipe Cleaners
This should match the color of your costume. Thin pipe cleaners work well, you just need to buy enough of them to twist around to make a solid and flexible pair of antenna. Some glittery pipe-cleaner is also helpful in complimenting the solid colors.

Other materials:
Hot glue gun
Needle and thread (or staples)
Safety pins (various sizes)
A friend (very helpful to have someone to wear the costume as it is being created)
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gryphyn made it!5 years ago
Just wanted to share my version. I used adhesive velcro to hold the sides shut and a 10" Styrofoam wreath wrapped in duct tape for the mouth. After gluing have of the wreath for the mouth edge, you can hold the other half and flip it up and down. Sorry the pics are sideways. I can't sort out how to rotate it since they appear correctly oriented on my Mac.

jen.maitland made it!5 years ago
Hi there,
Thank you very much for these instructions! my sister have made 2 yip yip costumes for this halloween (2009).
a few things we did different were....
1. we sewed up the sides of the costume....we found that this was harder to get into but it became more sturdy....we left a 8" gap so our arms can come out but it folds over so you can't see the gap.
2. we couldn't find a foam peace so we purchased some 1" styrofoam and made it into tombstone shape and placed a stick in the middle, wrapped it in duct tape and attached it to the mouth.....still allowed it to be flowing and allowed for a handle as well.
3. we wraped gardening wire around the pipe cleaners so that we could get more structure in the cleaners themselves.....
Here is how one of our costumes turned out!
kqrpnb made it!5 years ago
Here's my Yip Yip.  Made it in just a few hours.  Here's how I modified the instructions for my budget:

1. I bought regular Fleece instead of curly fleece.  It's cheaper, plus we found it on sale.

2. We put up 4 layers of black chiffon for the face, but so far we've cut on layer off from the inside cause it's a bit too dark.  We expect maybe one more layer will come off by Hallowe'en

3. For fit, I started the fabric in the back just about touching the floor.  Then up over the head, grab the 'mouth' where it's comfortable and fold your arms to under your eyes. Trim the front to the same level as the back (you may want to wait until you are done constructing the mouth though)

4.  I sewed up the sides instead of pinning.  After you finish the mouth and get the cap on right (we safety-pinned a baseball cap turned backwards), make sure that the fabric is at the same level at front and back with your lower jaw in place just below YOUR eyes (not the yip yip's - you want the jaw where you can see over it to walk).  Once that's trimmed level, just flip the costume inside out, hold the corners of the front and back together and sew a half-inch seem all the way up to about 20" from the fold.  Don't over-complicate this: Imagine folding a bedsheet in half, then sewing a half inch seem from the open end to the closed end, ans stopping 20" before getting to the closed end.  This leaves room to poke your arms out, but is loose enough to hide your shoulders if you tuck it in.

5. Antennae: take two pipe cleaners and hook them together end to end to make a long one.  Make 5 or 6 of these, then twist them together in pairs, then again, until all are twisted together as one sextuple-thick, double-length pipe cleaner.  Take 2 more and wrap them around one end to form the pom-pom.  This makes ONE antenna.  Do it all again for the other.  What I did then was to put these two together and wrap another pipe cleaner around the end to bind them together.  This will make a V-shape out of the antennae.  Now make a small L on the bound-together side.  This gets glued to the fabric, and the rest of the bound portion gets glued to the back of the eye-balls where they meet.  this gives a lot of stability to the works, plus it let's you curve the antennae around the eyeballs like the real yip yips.

6. Mouth modifications:  Now that the costume is all sewn up, but before you glue the eyes and antennae on, I made one practical change.  Find the inside bottom point of the mouth when it is in position under your eyes.  Sew through the chiffon a 3"-4" diameter circle centered around that bottom point.  Then cut an X through the chiffon circle, and safety-pin a pillow case to the inside of the costume so that it catches whatever candy is thrown into your mouth!
Rachyl is a Yip Yip.jpg
Emaleen kqrpnb5 years ago
 Does adding the pillowcase have to be done before adding the eyes and antennae? 
kqrpnb Emaleen5 years ago
 Thanks Sliny!

@Emaleen: I would do every single thing you can before attaching the eyes and antennae.  You should make sure everything works as you want it, then glue the eyes and antennae, otherwise you stress the hot glue when you turn it inside out or take it on and off.  You know?
sliny (author)  kqrpnb5 years ago
great job, especially on the pillow case. :)
Peekadosies made it!5 years ago
heres my yip yip costume
nice instructables
KualoJo made it!5 years ago
yip yip!
redstarsrbija made it!5 years ago
GREAT INSTRUCTABLE! I made one of these suckers and wore it to my college all day on Halloween lmao such great reactions! I even mastered the yip yip speech lol I used a tennis racket for the mouth, made it ALOT easier lol the chick on the right seemed to like my costume so she wanted a picture
sliny (author)  redstarsrbija5 years ago
Nice idea with the tennis racket. You do lose one thing though, with the soft squishy sponge, lots of people come by and giggle when they squeeze your "lip". :D
Yould you please make an instructable on it please
lol i used this one right here. what difference would it make if i made one?
I commented earlier and I asked for a yip yip hat.You see?
Spifferoo made it!6 years ago
Thank-you for this great idea! We also won best costume. A four year old just loved us and asked if we were in costumes ... he was so convinced we were martians!
NCBob made it!6 years ago
Awesome instructable. A friend and I at work made them and entered our costume contest and we won best group costume :) Only thing we did different is we used a sewing machine to sew the mouth, it was much faster and turned out great. EXCELLENT instructable!!!
NCBob NCBob6 years ago
(removed by author or community request)
sliny (author)  NCBob6 years ago
Awesome! Congrats on the award!
NCBob sliny6 years ago
Ok, got the full video of the skit and uploaded it. Even though they introduce us as the Yip Yaps :)
noelrossiter made it!6 years ago
Thanks - a wonderful set of instructions. Here's my creation used at a 40th birthday party (TV themed) last weekend in Hobart Australia
sliny (author)  noelrossiter6 years ago
Awesome work, I'm sure you had alot of fun with that!

Oh my god, I love the aliens! Do you remember the one that goes,
"Ra-di-o!"? You did a fabulous job, and thank goodness the kids went
for it! It's uncanny how much it looks like the yip yips. :)

pingh made it!4 months ago

This was such a great idea. Based on the items in the comments, we used velcro as well to hold our mesh in place. We used a single layer of black chiffon for the mesh which was easy enough to see through while nobody could see in.

Great times indeed.

MelissaB35 months ago

where could I buy this in winnipeg

MelissaB35 months ago

where would i buy this in winnipeg

CelineVerena made it!11 months ago

Thanks a
lot for these awesome and useful instructables. We also won the Best costume

A few
things we did differently:

We stuck the layers of black mesh together using hot glue instead of tape
& we did not sew the mouth to the fabric, but we used velcro strips, which
we stapled to both the fabric and the black mesh.

2. We
attached the eye balls to the fabric using hot glue and pins which we stuck
from the inside of the costume through the beanie and the fabric into the
Styrofoam eye balls. This worked out well.

3. We
attached the eye balls to each other using double-sided tape and a toothpick, because
the hot glue made the Styrofoam melt. Double-sided tape and a toothpick weren’t
enough to hold the eye balls together the whole evening, but we had some extra
double-sided tape with us;)

4. We attached
the antennae to the eye balls using pins. This didn’t work out too well,
because the pins kept coming loose.

5. We didn’t
seal up the sides with safety pins, but wrapped the back part of the costume
around our waist and attached it with a safety pin on the front side. A lot
easier and works well too;)

ttttiff1 year ago
on the previous step i noted the fragile state of our eyes, so what ended up working for us here was to hot glue (on low temp setting) the eyes to the antenna. we created a little semi-circle, c-shaped, base with the end of the pipe cleaner, and set the eye on top, secured with the glue. then we trailed the antenna up the back and secured the antenna with sewing pins criss crossed into the eyes. liquid nails would also work better for this. we hot glued (high setting) the base portion we created with the pipe cleaner to the top of the head and put some extra glue around the bottom to kind of "seal" it. then we just shaped the antenna out. they held all night.
ttttiff1 year ago
we had quite a time trying to attach our eyes. the hot glue was just melting the styrofoam. we tried tape and super glue also, with no success. on one, (due to damage between the eyes caused by the hot glue) we ended up using liquid nails, which kept them pretty damn solid all throughout the night. on the other costume, there wasn't as much damage, so i used a tooth pick to connect them (half the tooth pick in each eye) in the center and just put a little of the liquid nails in between, just in case.
mothman01 year ago
Can you clarify where you suggest pinning the weight to weigh down the mouth?

Is it attached to the approximate center of the black fabric?
dwelch11 year ago
Can't wait to make these....
I LOVE this costume idea! My boyfriend wants to make this to celebrate 'carneval' in the Netherlands, can't wait untill february!
Mostmom1 made it!2 years ago
Thanks again for a great instructable! We had SO much fun with these!!
IMG_3006 - Version 2.jpgIMG_3007.JPG
Mostmom12 years ago
I made these for my daughter and her best friend this year. People loved them!! We used half a styrofoam ring on the inside for the mouth, regular fleece, and those gigantic pipe cleaners for the antennae. We bought 6 yards for each costume and had a lot left over. We used two layers of chiffon for the mouth and they ripped one off, after it got dark, so they could see. This was a toasty warm/dry costume too, which was good, since it was a cold, wet Halloween.
It's a costume, it's a muppet, it's awesome. :)
mausmobile2 years ago
My husband and I just got home from a Halloween costume contest. I still can't believe it - we took first place!

People loved the costume, but I think they loved the act more. We walked around the bar several times, looking things up in our book, yipping at people, and letting them take pictures with us. There were some pretty elaborate costumes, but ours had the most character.

Thanks so much for your awesome instructable. You helped us turn our idea into reality!
jfaulstich3 years ago
Here's my attempt at the Yip Yips. My neighbor and I worked on these in one night. It took about 4.5 - 5 hours.

It was also insanely expensive. Not many places sell the curly fleece anymore, and the one place we could find (JoAnn Fabrics), only had it in one bright color, red. The rest of the colors were off-white, white, brown, and spotted, so they weren't exactly traditional Muppet colors. We purchased the red curly fleece (at $75 for 6 yards) and then opted for a cheaper, yet similar material in pink ($45 for 6 yards). I would strongly recommend using a cheaper material like Crushed Panne Velvet. It comes in a variety of colors and is more breathable. The only downside is that it doesn't hide pins, glue, etc. as well as the curly fleece.

In the end, the effort and money spent were pretty well worth it. People were beyond giddy at the reference (if they got it...we got a lot of "Elmo!" and "Hey Cookie Monster!" too) and were amazed we made them ourselves. My only regret was not enrolling ourselves in a costume contest or 2. Given the cost of the costumes though, I plan on using this for many a costume party and Halloween for years to come. Thanks for this Instructable!
blatour23 years ago
Me and my friend Anjali made these for halloween! We are both 12 and we know the yip yips because my dad used to watch them when he was little! :) I would upload a pic but I don't have one on THIS computer, hopefully somtime I will be able to uplad it! Thank instructables!! (:

vdillon13 years ago
Where do you guys find the curly fleece at? I can't seem to locate any.
sliny (author)  vdillon13 years ago
I found it at JoAnns fabric stores. I would think that the larger retailers would have them, or at least something similar in quality.
cazeliea3 years ago
Help! I am really eager to make this costume, but the only two fabric stores around me only carry this fabric in red, black, brown, white, and gray... ! I'm making one for myself and someone else, so I don't want to have two red yip yips (and those other colors are definitely not yip-y enough).

Does anyone remember the name of stores they found their curly fleece from? I'd love to email those stores or call them and see if they have any. Once I saw the curly fleece in real life, I really, really don't want to use a stand-in fabric.. the curly fleece is so good!

Thanks for any help!
sliny (author)  cazeliea3 years ago
I found it at JoAnns fabric stores. I would think that the larger retailers would have them, or at least something similar in quality.
solemnraven3 years ago
That's so awesome.
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