Marty: "Doc, Doc, Biff's goons are gonna jump me" Doc:"Then get out of there!" Marty:"No, not me, the other me, the one up on stage, playing Johnny B. Goode" Doc:"Great Scott, if your other self doesn't return to 1985, We'll have a huge paradox." Marty:"A paradox, you mean one of those things that could destroy the universe?!" Doc:"Precisely!" Marty in sarcastic tone:"Perfect!"