1: Photo bombing.
Waiting for someone to take a shit and then barge in with a camera and take a picture of them pooping. Preferably in a public place with strangers. I have an entire collection of pics that I share with my 'acquaintances' at our 'wine parties'. We trade them like Pokemon cards. Good times.
2: Tickle butt
I go to clubs then get behind a guy and tickle his ass, then hide in the crowd so he doesn't know it was me. Hours of fun.
3. getbig.com
Hope that helps