I'm going to say those little fish from Hydro City Zone in Sonic 3, mainly because they had a glitch where they would get stuck on Sonic, rendering him unable to jump to get an air bubble so all you could do was to sit there and wait for the drowning music to start...
EDIT: I've just checked and it's apparently not a glitch, what the hell Sega
EDIT: I've just checked and it's apparently not a glitch, what the hell Sega