John and Mary went to a bar. They had some drinks, a few laughs, and finally were ready to leave. Mary pulls out her purse, but then John says, "No I'll pay." So he says to the bartender, "Do you accept Bitcoins?"
"What the hell's that?" "It's a crypto-currency that you can mine and it creates 256 bit encryption keys, decentralized and it has no fees." The bartender and Mary give John a weird look. John says "Look, want to see my GPU?"
He reaches into his coat pocket to pull out his spare Radeon HD 5770. The bartender blinks. Mary says "Ok, I'll pay." and hands the bartender two twenties. She then says to John, "You're such a freak." The end.
Source : https://bitcointalk.org