Japan is crazy, and I say that with love. Here are some examples, enjoy. 

Flash Mob

http://www.youtube.com/watch?v=bj0Ma2CsHME

Toilet Prank 

http://www.youtube.com/watch?v=YsDbOMJOMgQ

Spa Prank 

http://www.youtube.com/watch?v=omu4G8igoVc