The Dark Backward

The Dark Backward is a 1991 satirical comedy film directed and written by Adam Rifkin, with special makeup effects by Alterian, Inc.

One day, Gus convinces a talent agent, Jackie Chrome Wayne Newton, to check out Martys act. Jackie isnt impressed. Martys luck seems to take a turn for the worse when a large lump starts growing on his back. He goes to a quack doctor James Caan, who calls him a wimp and puts a BandAid on the lump. The lump continues to grow, eventually becoming a fullsized arm. While Gus uses Martys newfound freakishness to impress his morbidly obese girlfriends, a horrified Rosarita breaks up with Marty, and he gets fired from the club where he does his act.Marty is despondent until Gus brings him to see Jackie, who, it turns out, has always dreamed of finding a real threearmed comic. Rechristened Desi the ThreeArmed Wonder Comic, and with Gus now providing musical accompaniment, Marty gets a fresh start on his career. Marty and Gus have a few semisuccessful shows and eventually meet Hollywood talent agent Dirk Delta Rob Lowe, who offers them a job. Marty, Gus and Jackie celebrate this big break and everything seems to be looking up until Marty wakes up the following morning and discovers his third arm has inexplicably vanished. ........

Source: Wikipedia