Collective Roleplaying is a term where every aspect of the RPG is owned by everyone who participates. All characters may be controlled by all players, no matter who brings in the character. If the game is turn-based, then each player may modify the last play by making the character do something different. The last play is still valid, but the next person may change the course of the character's actions. Or the next player may choose to use a different character. If the game is not turn-based, then the first person to get to the character has the right of way, which gives a competitive edge. If you were at a disadvantage on controlling a popular character, go for the least popular characters; this way you have an actual advantage.
In Collective Roleplaying you may make the characters do anything you want, since everyone has the chance to use them.
This type of game can be really ridiculous, due to the nature of the game. But that is the whole point really.
That collective roleplaying game was ridiculous! It caused everyone to get very angry at each other...