Here are some comeback answers:
– You haven’t asked yet.
– I was hoping to do something meaningful with my life.
– Because I just love hearing this question.
– Just lucky, I guess.
– It gives my mother something to live for.
– My fiancée is awaiting his/her parole.
– I’m still hoping for a shot at Miss/Mr. America.
– Do you know how hard it is to get two tickets to Miss Saigon?
– I’m waiting until I get to be your age.
– It didn’t seem worth a blood test.
– I already have enough laundry to do, thank you.
– Because I think it would take all the spontaneity out of dating.
– My co-op board doesn’t allow spouses.
– I’d have to forfeit my billion-dollar trust fund.
– They just opened a great singles bar on my block.
– I wouldn’t want my parents to drop dead from sheer happiness.
– I guess it just goes to prove that you can’t trust those voodoo doll rituals.
– What? And lose all the money I’ve invested in running personal ads?
– I don’t want to have to support another person on my paycheck.
– Why aren’t you thin?
– I’m married to my career, although recently we have been considering a trial separation.
– Bonus reply for Single Mothers: Because having a husband and a child would be redundant.