I think if you are referring to the shirt where you see the number 12 on the jersey of the player in the tunnel, then the number 12 is referring to the fans or the 12th man as they have been called.
sharply
Tyler
Rees
Tyler
Paul Hornung
lun
Emitt smith
its the two one side
joe Montana
Joe Montana-Notre dame
Tom Gatewood wore 44. Gatewood was an all American receiver at Notre Dame in 1969-71. Joe Theisman was the quarterback.
Quarterback Jimmy Clausen most recently wore #7 for the Irish.