The member of a pair destined for lesser things. A reference to the 80's and 90's wrestling tag team The Rockers. Shawn Michaels went on to greatness, while Marty Jannetty faded into obscurity.
"That guy from Wham who wasn't George Michael was totally the Marty Jannetty of that group."
"Bob Odenkirk was the Marty Jannetty of Mr. Show."
"In the end, Emilio Estevez was the Marty Jannetty of Martin Sheen's kids."