Jerry Lewis' next acting gig is no laughing matter.

This fall, the 80-year-old comedian will play the homeless uncle of Richard Belzer's police Detective John Munch in a guest spot on "Law & Order: Special Victims Unit," an NBC spokeswoman said Monday.

In the episode titled, "Uncle," detectives find Lewis' character living on the street and arrest him as a suspect in a murder case.

Lewis took a dramatic detour in 1983 as a talk-show host kidnapped by an aspiring comic, played by Robert De Niro, in Martin Scorsese's "The King of Comedy."

Belzer will lead a Friars Club celebrity roast of Lewis in New York on June 9.