"Hey dude, better keep your back against the wall in the showers today"
"Why?"
"Randy went into the locker room a few minutes ago"
"Thanks for the heads-up. I heard he's a real bum dart champion"
In any video game (typically Halo: Reach), offering one of your teammates as bait to the enemy team by standing perfectly still, then proceeding to kill the idiot who tries to kill the bait.
"Stand with your back to the enemy so they'll come over."
"Why?"
"So you can be bumbait!"
What you call An idiot who does all ofthe above: Has dinner at your house every night , smells like shit , looks even worse , gf dumped him , and wheres to much colonge/aftershave