One of the most time honored and one of the oldest forms of comedy, improv, is perhaps the most powerful of all methods. More than once have I been captivated by shows on comedy central based on improv: Whose Line Is It Anyway (british versions are better, foo'), Make Me Laugh, and various live shows that I have been fortunate enough to see.
There is also another form of comedy, the prank, which is perhaps the most practical of all forms of entertainment. Its very popular at college through the act of "drunken shaming," tin foiling rooms, and my personal favorite: hiding hundreds of troll dolls in your room mate's drawers and bed. (Okay, perhaps more creepy than funny, but we had a good laugh.)
A new york based comedy group called
Improv Everwhere, this group combines the two comedy forms into one big super ultra mecha comedy amalgum of dooooooooom. In all seriousness, these guys are the funniest thing on the net since AYB, they have videos of their some of their pranks, check em out, kay? I highly suggest: Ben Fold Last Night In Town, and The Amazing Hypnotist (video).