cats are assholes

There are medical things such as bladder infection or UTI that can cause this as well, but I agree with DaLiNkWeNT.

.....

Vouch, my mom cat actually stresses so much during/before the vet visit he consistently poops himself lol.

this

Sometimes animals can sense your mad at people & will poop &/or pee where they sleep.

known reasons that i can think off the top of my head

mad at you

doesnt like that litter/or scent from the litter

it doesnt find the litter clean enough.

scent of another animal

cats are nasty get a dog

only reason is because it doesnt like the litter box
ive had my cats poop on the floor near the box if it was dirty

but like the other guy said, it might not like the litter