I saw a young teen spot a watersnake (non poisonous) in a pool. He yelled "hey, a snake" and grabbed it by the tail end. Wow, did that snake turn fast. It grabbed him and he just about jumped out of the water. The snake left about 100 teeth in his hand (yes, if you grab a snake and pull him away, the teeth stay behind - but only non-poisonous snakes). He had to get the teeth removed and a tetanus shot.
I've seen that happen twice. once with an 8ft King Snake.
I've also seen a teen try to grab a chipmunk as he thought it was "cute" and it seemed to be cornered. It took over 100 stitches to close him up from wrist to shoulder. Oh, did I mention the tetanus shot and the rabies shots?