I don't know if it's just cuz everyone jumps in on the pitbull stories, but there's a lot of them.
Another is a girl hanging out on couch with her pet pitbull, owned since puppy. pitbull has a violent spasm, ripping up her face, biting her lip off. 10 secs later pitbull acts totally normal as if nothing happened.
It's nothing personal with these dogs; it just seems as though selective breeding has encoded some violent surprises into the breed. and from what i've read, there are breeds more prone to biting, but with pitbulls the damage is severe because of their aggressiveness and jaw structure.