Comeback advice

There is a very obnoxious boy who insists on making sex noises Avery time he stretches, and it absolutely drives me insane. He was doing it at me this afternoon while I was using the pencil sharpener, and I held the pencil low enough by my side that it would not be perceived as a threat, and I said, “I’ve just about had it with you!” And stormed off back to my section on the countertop where I stand. The teachers haven’t done jack shit about this for 3 years, and I want comebacks for when he does it, because it’s annoying as shit. Any witty comebacks?