What's the best comeback that you've ever heard/used?

My favorite so far comes from my sister. Her Latin class was small enough that it would double as study hall for non-Latin students. One of these students, presumably in pursuit of a point, was going on about how “her people” (that is, Caucasians) had enslaved his (that is, Blacks). She turned to him and said, “No, my people enslaved Adam’s people” here she pointed to a young man of Gallic ancestry, “and made them dig tunnels through the mountains.”