In Wild in the Streets (1968), his character Billy Cage was asked how long he thinks he is going to live and he replies "Thirty, man." Coughlin was later killed in a hit-and-run accident on January 19, 1976, only five weeks after his 30th birthday.
His handicap limp was incorporated into the script of his memorable childhood role of T.R. Ryan on TV's "Mama".
He died from multiple injuries from a hit and run accident in Los Angeles.