Ironically the original script was just "Some kind of frightened scream", and the idea was you can optimize that one by going for the second exit first - which made it into the game - but when we went over it in the makeshift recording booth they just flashed one hell of a grin.
They then proceeded to get in the booth and drop the line "WHY IS IT CALLED A RESTROOM, I'M FIGHTING FOR MY LIFE HERE" and I absolutely had to use it.
They cooked with that one.