Marty: "Doc! Doc, come in!"
Doc: "Marty, come in."
Marty: "Listen, Biff's guys chased me into the gym and they're gonna jump... me."
Doc: "Then get out of there!"
Marty: "No, Doc, not me. The other me. The one that's up on stage playing 'Johnny B. Goode.'!"
Doc: "Great Scott!"