I have come to love japanese people more and more as I see the ridiculous things they get away with for the sake of comedy. If you haven't seen any of these clips on YouTube... brace yourself, they are HILARIOUS.
I'm of the opinion that were you to try these in the USA... you'd get yourself shot.
The newest one I've found... scare the crap out of someone using large groups of people:
The classic Japanese Spa Trick (my personal favorite):
and the somewhat sadistic Japanese tongue-twister prank:
and the ever classic HUMAN TETRIS!