John needs a ride to the airport and asks his buddy Paul to give him a ride. Paul says, "Okay, but you need to give me a ride to the airport next month when I go to my sister's wedding." As John gets out of the car at the airport, he declares, "I owe you one, mate." When Paul asks John for a ride to the airport, John turns him down, explaining that he's got a date. John is not legally enforceable because no monetary consideration was paid by either party.