I like to tell them that the only way I can afford my studio apartment is to have a second job as a waitress. That always shocks people.
The other day I had a flight attendant complain about how much she makes and that she never tips the van drivers because she can't afford it. She got all "woe is me" on me and started trying to guilt trip me because I make so much more than she does. It turns out the woman makes almost 50% more than I do. I don't think she quite understood the ridiculousness of the situation but at least now she knows.