My first playthrough, I take everything all serious and try to make a character that looks like me (so, a white dude).
My second playthrough, I max out every bar on the character sliders and play like that. If that's not ridiculous enough, I'll mess with it more until it is ridiculous.
Also, in Mass Effect 2, there's this weird code thing at the bottom of the screen that shows what code your character is. It's absolutely useless, but for my girl character I put in the Lost numbers (4, 8, 15, 16, 23, 42) and came up with a pale white woman who was balding and had deep red eyes. Shit was weird.