Carl Reiner directs Steve Martin (who co-wrote the script with Carl Gottlieb) in this gag-laden comedy about an idiotic white man, raised by a poor family of black sharecroppers, who doesn't realize he's not black.
Navin R. Johnson (Steve Martin) is told the horrible truth when he finds himself instinctively tapping his feet to an easy listening tune on the radio, instead of a low-down blues.
His mother (Mabel King) tells him he's white and Navin takes to the road (in a World War II bomber helmet and goggles) to start a new life in St. Louis. A filling station owner, Harry Hartounian (Jackie Mason), give Navin his first break, hiring him to pump gas.
One day at the station, Navin has a brainstorm, concocting an invention called The Opti-grab, a combination handle and nose-brace for eyeglasses. But Navin runs into trouble when a crazed killer (M. Emmet Walsh) picks out his name at random from the telephone book and tries to kill him.
Navin escapes to a traveling carnival, where he wrangles a job as the guess-your-weight man. At the carnival, he discovers his sexual nature, thanks to stunt rider and S&M enthusiast Patty Bernstein (Catlin Adams). But Navin meets the beautiful Marie (Bernadette Peters) and he quickly falls in love.
In the meantime, the Opti-grab has taken off and soon Navin is a millionaire.