Raccoons!

[locusts]

There's a wild raccoon on the station! It lives in one of the disposal chutes, but exactly which one changes each round. It holds on to things put in the disposal chute and eats food. Sometimes if you walk past the one it's in it'll drag you inside and grab the things you were holding. If you eject it from the chute it runs away! And of course, its tiny powerful hands have evolved in space to grip the inside of the chute, which means it cannot be flushed.