Kenneth Keith Kallenbach, an actor, comedian and long-running member of Howard Stern’s “Wack Pack,” has died in custody. He was 39.

Kallenbach, who was arrested in March for allegedly trying to lure an underage girl into his car, contracted pneumonia at a prison outside Philadelphia and died April 24 at a suburban hospital, said his mother, Fay Kallenbach.

Stern first reported the news on his Sirius Satellite Radio show Thursday.

The long-haired Kallenbach, whose goofball antics included attempting to blow smoke from his eyes, made dozens of appearances on Stern’s show beginning in 1990. Stern once likened him to MTV’s Beavis and Butt-head and wrote in his book “Private Parts” that he was the “ultimate airhead.”

More recently, Kallenbach, of Boothwyn, Pa., starred in commercials for ESPN’s “Monday Night Football” and Stride chewing gum. He also appeared on Jay Leno’s “Tonight” show and had uncredited parts in HBO’s “Sex and the City” and the film “Jerry Maguire.”