I would say peed on my brother’s bed.
Lol!
My cat has scratched the heck out of me on many occasions. She’s also clawed the finish off a door, while scratching at it all night to get in. This is probably the worst/most annoying thing a pet has done. She’s also sneezed in my face multiple times.
My dog has barked ferociously at babies/toddlers/strollers. Obviously when she was a puppy she peed everywhere and once decided to chew pieces off a wall. She also liked to chew electrical cords. Let’s just say puppies need constant supervision. She barks a ton but I’ve adapted to that.
There are just so many things but luckily non of them have been too terrible 
I’ve only had small pets so they haven’t done hugely terrible things, but these are the worst things they did.
My first hamster, Hammy, chewed an little archway in the bottom of a door when he escaped one night.
My second hamster, [name_m]Prince[/name_m], chewed the corner off a duvet cover to use as bedding.
My fourth hamster, [name_f]Zoey[/name_f], bit my dad - the only time she ever bit in her life.
My fifth hamster, [name_m]Oreo[/name_m], bit a chunk out of my boyfriend at the time’s thumb (she thought he was chicken, she was vicious around chicken). She also knocked over a glass of whiskey and then proceeded to drink it (she was fine).
My budgie, [name_u]Joey[/name_u], pooped on my dad’s head, more than once.
My guinea pig, [name_u]Cody[/name_u], peed on my sister’s friend’s lap. He was potty trained by that point so we took it as a sign that he didn’t like her. [name_u]Cody[/name_u] also once chewed the corner off my homework, and my teacher didn’t believe me when I handed it in and said “my guinea pig tried eating my homework”
[name_f]My[/name_f] cat [name_m]Huckleberry[/name_m] climbed into a hole in our basement ceiling and got stuck in the ceiling for a few hours. This happened more than once.