Munch Kin

A MunchKin is a RolePlayer? who plays to win, rather than to play, and is generally fairly clueless about anything not explicitly laid out in the rulebooks.

MunchKins treat RPGs as games, not roleplaying.

See:

http://acasun.eckerd.edu/~dagorhir/articles/munchkin

The key quote from this is perhaps "whatever gives the most pluses"!

See also:

A tongue in cheek book about how to be a munchkin: http://www.sjgames.com/munchkin/guide/

A humorous card game about being a munchkin: http://www.sjgames.com/munchkin/game/