The cute young black girl working the register tried to get me to sign up for 3 free months of AOL (would you like fries with that?) while I was swiping my card to pay. "Ohhhh no," I replied, in no uncertain terms. She could tell how amused I was at the very idea, and apparently decided that I must have thought she was trying to extract more money from me. So she reassured me "but it's free!" - and I cheerfully replied "sure - but so is the clap," with my friendliest just-being-mischievous smile to take the sting out of it.
She actually blushed, grinned back at me, and said "words to live by."