This is an AWESOME instructable. The effect is you put your fist to your mouth and puff out your cheeks. You take your fist away and smoke comes out of your mouth. Please excuse the photos. They aren't mine. I don't know how to put photos on here.
Step 1: Preparation
NONE! Unless you count making your hand into a fist. So then, the preparation is to make your hand into a fist. Be ready to put your fist where your mouth is.
Step 2: Put your fist where your mouth is
Now, after you have made a fist with your hand, put your fist where your mouth is: the side of it, where your thumb is. Do it just like in the picture. It's so easy, a baby can do it!
Step 3: Blow
Puff your cheeks out REALLY hard like the kid in this picture, but don't make it hurt too much, I don't want any exploding cheeks. This part is the hard part. Inside your mouth, you are actually squeezing the air into what is called fog. As you should know, fog is just water, or in this case, spit (I think).
Step 4: Open your mouth
After you have finished the other steps, take your fist away and open your mouth. Don't breathe out. The fog should come out of your mouth naturally. One last tip while you are blowing against your fist: Don't breathe. I know you think you'll look like this fish holding it's breath but if you breathe, you'll mess the whole thing up because the fog will just travel down your lungs. It doesn't matter if you breathe through your nose or not, your nose is connected to your mouth so it would still mess it up.