Wall of Death

Wall of Death (Moshing)

"Moshing refers to the act in which the audience members at live music preformances push and/or slam into each other for the purpose of entertainment."

http://en.wikepedia.org/wiki/moshing

Flash Mob

" A large group of people who assemble suddenly in a public place, preform an unusual and pointless act for a brief time, then disperse."

http://en.wikipedia.org/wiki/Flash_mob