After the first torture session with Ocelot, if that player runs around the cell, perform attacks inside the cell, or knocks on the cell walls, the guard will yell at Snake to be quiet.
Hiding under the bed while he is still watching you will also make him comment at Snake, saying "What the hell are you doing?", and using the Ketchup while still in his view will make him say "What are you playing around with that Ketchup for?"