Imagine this: You go to your bathroom and sit in the peace and tranquility of your toilet when... a big splash of water falls from the roof and make you look like a wet dog!!!

Well, this was an annoying prank when I was in the Navy, and watching "Lethal Weapon 2" gave me the idea: if I could make the same joke, but activated when the guy sits in the toilet? MUAHAHAHAHAHAHAHAHA!! IT'S PAYBACK TIME!!!

This devilish prank works in this way: when the victim sits in the toilet, press a switch. The switch activates a motorized device, disguised as a first aid kit in the top over the toilet, and drops a big splash of water.

BUT WAIT!!! I want to say to the victim "HEY! YOU WAS MY VICTIM!". I want to say "IN YOUR FACE!!". I want to say "YOU'RE MY B...!!!".

And for a geek, all those sentences are summarized in one single word: "BAZZINGA!!!"

So, when the water drops, immediately a "Bazzinga!" drop-sign will fall. And the poor wet human will be noticed that he has fallen for one of my classic pranks (thanks, Sheldon Cooper!!)

(NOTE: Because the victim did not give authorization for upload the video of the prank, you will see me making the demonstration of how it works. I put together the white box and the drop-sign for seeing how it works, but you can place it where you consider it will look better).

Step 1: Materials, tips and warnings...

Like always, we will use ordinary stuff and trash. Remember: loose engineering; If you don't have it, replace it or make it. These are the materials:


- Plastic box (If you have a first aid kit or another box that looks good for the prank, use it. I did not have it, so I had to make one).
- 1 Plastic glass (you can use small plastic bottles)
- 1 Electric screwdiver, a hacked servo or a motor with reduction gears.
- 1 Plastic piece for the "arm" that push the glass with water.
- 4 mts of wire
- 5 Metallic angles
- 2 switches: one thin for the toilet and one for the motor "arm". I don't know the reference, but you will see the switches in the pictures.
- 2 hinges
- 1Battery box (for 4 AA batteries)
- 1Plug (for connect the White Box to the "Bazzinga" Drop-sign)
- Red and white paint
- Duct and masker tapes
- Soldering tin
- nuts and bolts
- 1 metallic plate, for fix the screwdiver to the box.


- White cloth (big enough for the sign)
- Markers
- 1 Printer plastic piece, or a rectangular PVC pipe
- 1 Electric screwdiver, a hacked servo or a motor with reduction gears.
- 1 Plastic piece for the "arm" that push the drop-sign
- 1 switch for stop the motor "arm"
- 50cm of PVC pipe (for the end of the drop-sign)
- Keyboard below plastic plate (or a rule, for the top side of the drop-sign)
- Aluminum paint
- nuts and bolts


Rotary tool, screwdivers, heat gun, soldering iron, tweezers and pliers.


- If you need instructions of how to assemble plastic pieces using nuts and bolts and how to hack an electric screwdiver, please visit my instructable "Become a mad cyborg...":

Assembly: http://www.instructables.com/id/BECOME-A-MAD-CYBORG-part-human-part-dead-compu/step1/A-lot-of-useful-and-important-blablabla-before-sta/

Hacking electric screwdiver: http://www.instructables.com/id/BECOME-A-MAD-CYBORG-part-human-part-dead-compu/step3/MECHANICAL-ARM-option-B-motorized-action/

- Before starting, read carefully the instructable. Then, go to your bathroom and look how to adapt this idea to your WC.

- Because I was over time, I did it disguised like a first aid kit. You can disguise it like a kleenex box, or another bathroom decoration.


1. Always use personal protective equipment (goggles, dust mask, gloves and others), specially when you use rotary tools.
2. Work in an area with good ventilation
3. The things warmed by a heat gun or worked with a rotary tool could be very hot. Be careful when manipulate!
4. Water can damage electric and electronic devices, with risk of shock and injuries. Don't do this prank near electric stuff.
5. The Red Cross Symbol is internationally protected, and its abuse or use in pranks could be punished by the Law. Try to use another symbol.
6. Always keep a real first aid kit in your home. You and your family must know where to find it.
7. Fix the box to the wall or to the cabinet. Use screws. Why? because the force of the bottle fall will make the box go forward, and fall over the victim, causing injuries. You will see the effect in this video

All right... LETS DO IT!

It Bazinga. There's only one Z
That's not how u spell it
Or, suppose, just suppose, just for the sake of supposing, what if u filled the bottle with pee? that was NOT a suggestion. DON'T do it.
hot damn. when i get to college, my roommates will hate me for this one...
LOL!!!<br /> <br /> Good luck ilpug!!<br />
Bazzzinnngaaaaaaaaa!!!!!!, muy bueno...&nbsp;
Gracias!!!!! BAZZINGA!!!<br />
&nbsp;Por ac&aacute; como siempre apoyando tu talento Se&ntilde;or Mario!!<br /> <br /> Excelente... Bazzinga!!<br />
Gracias, muchas gracias se&ntilde;orita Stark!!!! BAZZINGA!!!!!<br />
&nbsp;Got my vote dear!!!!! as always.....&nbsp;
Thank you, Miss Bolivar!!!!<br />
&nbsp;This is the BEST Mario!!!!!!!!!!! &nbsp;Just one question: why do you use the toilet with your pants on? ;o)<br /> <br /> YAY &nbsp;Mario!!!!!!!! &nbsp;The most fantastic junk builder in the universe!!!<br />
Gracias, muchas gracias, mi hermosa StitchDiva!!<br /> <br /> It was a dramatization, because the real victim didn't want I upload the video. So, I had to make the demostration. LOL!!<br /> <br /> AND THANK YOU!!&nbsp;I FALL IN LOVE!!!!!!<br /> <br /> I'm the Junk Master of the Universe!! ;-)
Como siempre!...FELICITACIONES!...ahi puse el segundo voto!...je je je
Gracias Pipe!!!

About This Instructable


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Bio: I'm Mario Caicedo Langer, from Colombia, former Navy officer and BSc in Naval Sciences. Right now I'm Technology Program Manager and Lego Robotics ... More »
More by M.C. Langer: Anti-cat countermeasures (kind of) Ultimate Robo-Planter (with light and detachable anti-spill module) Superheroic Wrist Gun (made of plastic trash and an old leather boot)
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