The best comeback ever is most likely: "The jerk store called, and they're running out of you." It's such a classic. Not vulgar nor violent. Hopefully they don't come back with "What's the difference, you're their all-time best seller." And always remember never to make sexual jokes about someone's wife because she may be in a coma.
Well I found the jerk store yesterday:
And conveniently, they also sell cold beer and wine.