Payback is a television show on the Speed Channel that debuted in 2006.
In the show, celebrities who have made it big pay back one of the people in their lives who in the past helped them along the way to their success, by building them a tricked out, one of a kind, new car designed specifically for them.
The show starts out by telling the story between the celebrity and the person who helped them out in the past (agent, parents, friend, etc.).
Then the celebrity states the plans for the new car, but leaves room for the build team to add in some cool extras.
This article relating to reality television in the United States is a stub.