Kelly

You and Kelly are good friends and have gone for a short break to a touristy city with a few other friends. You all gently wind up Kelly about his somewhat effeminate appearance and, following a long drinking session, you bet him quite a lot of money that he couldn't pass as a woman. Strangely, he accepts the bet. The next evening, you're all back in a bar in the main square except for Kelly. Just as your wondering if he's chickened out, an attractive statuesque woman approaches your table. You soon realise it's Kelly!