John and his cousin are car enthusiasts and they love to attend car shows. At a car show, John's cousin made him the following promise, "I'll buy your Chevrolet Impala tonight, if I do not spot one that I'm crazy about." In return, John agreed to sell his Chevrolet Impala to his cousin. John's cousin did not find a car that he was crazy about. If the cousin later refuses to buy John's car, can John legally enforce his cousin's promise?