What comeback went out so smooth and brutal that makes you smile when you look back on it?

It’s an oldie but I was in science class and a guy who picked on me asked to borrow my rubber (eraser) and he threw it across the room to give it back since I sat on the other side and I dropped it. He said, “You suck!” And I very bluntly said, “You swallow. ” The whole class went crazy and went “OOOOOOH” and others looked at me in suprise. I was the quiet kid, so they didn’t expect that from me.