You display three cards with the middle one being a different color than the rest. It also has a hole in it for easy identification. You get a spectator involved having them put their finger through the hole in the card and show it to someone else. Only when the second person starts laughing will they turn the card around to see that their finger is making up the “big part” of a naked boy.

Very easy card trick to play and ever so slightly rude too.
You get someone involved in your card trick during which they have to put their finger through the middle of the card and show it to someone else. Only when the second person starts laughing will they turn the card around to see that their finger is making up the key component of a naked boy.