95% of bites are just little defensive nips or feeding mistakes. Even the feeding mistakes aren't so bad, as long as the snake realizes it and lets go...
But I got my first serious bite this summer when I went over to a friend's apartment and was introduced to "Monty". Monty was an adult who'd been kept on a one-rat-a-month diet for two years because someone said he was "obese". And I had been handling exploded f/t mice early in the evening. He bit, he constricted, and he didn't let go. It was impressive. I still had a bruise under the skin a week later.