I've got a better true story from someone else, it might bring some disciplinary action down on me, though.
One of a gang of feral teenage girls was trying to embarrass a 'mature' traveller on the London Tube (subway) by offering a 'certain' favour for £10.00. His response: 'It'll cost you more than that, you little ~%@*~.'
Instant blush from her and silence in the carriage from then on except for stinging laughter from the other passengers. He was a guitarist btw.