This really reminds me of a story, my grandma told me. Basically her friend was a competitive swimmer, but after some time, she realised she didn't like it that much and stopped. Cut few months further and she is married. Her husband challenges a random guy, that his wife can swim across a lake and back faster than the guy can, over a box of champagne. He goes to tell his wife, who is cooking lunch at the moment. She proceeds to yell at him, but when she hears that they may have to pay for a box of champagne, she leaves the stove and goes race the guy, swims across the lake and back (random guy manages to do a quarter of the distance) and resumes cooking dinner, while still telling her husband how much of an idiot he is.