Premise: John Fair "Jocko" Marcellino (born May 12, 1950) is an American singer, musician, songwriter, producer and actor best known as one of the founders of the American rock and roll group Sha Na Na. He performed with Sha Na Na at the original Woodstock Festival, in the movie "Grease" and in The Sha Na Na Show, their worldwide syndicated TV show.
Hypothesis: John Fair "Jocko" Marcellino was a backup singer for the band Sha Na Na.