Super Smash Brawler Ball

It is the principal that everyone who buys a ticket to a football or rugby game has the right to play in the game. One of the ticket holders has to shout out 'Super Smash Brawler Ball' and then the arena becomes swarmed with all of the people in the stands and they beat the crap out of each other and have a fantastic time.

Spectator: Hmm, this is a fuckin boring game, SUPER SMASH BRAWLER BALL!!!.
All other spectators leap onto the field and join the game until there is nothing left of the arena.