games or sports you (or an acquaintance) played incorrectly or mangled with your own custom rules

when I went to summer camp, Four Square went from this simple game to having things like "contracts" where another player could 'hold' the space for you while you left the game, "four corners", and all kinds of wacked out shit. Tetherball, they added a proviso where you could catch the ball before sending it back (which was dumb). my next door neighbor changed the rules for checkers so you could jump people at the onset of the game (and got indignant when we called him on it).

what kinda games did you play growing up (or as an adult) where the rules were bent severely from how they are supposed to work? and moreso, did it improve the game or make it suck ass?

Subbuteo. Nobody I know played blocking flicks, which made for fast fun games. Later on, though, when we played people who actually knew what they were doing we looked like such amateurs. A friend of mine naively entered the national championships - played at John Menzies on Princes Street - and got beat something like 25-0.

game=monopoly, you=everyone: http://www.criticalmiss.com/issue10/CampaignRealMonopoly1.html