Then tell me, future boy, who's President of the United States in 1985? Ronald Reagan....

[Dr. Emmett Brown is doubting Marty McFly's story about that he is from the future] Dr. Emmett Brown: Then tell me, future boy, who's President of the United States in 1985? Marty McFly: Ronald Reagan. Dr. Emmett Brown: Ronald Reagan? The actor? [chuckles in disbelief] Dr. Emmett Brown: Then who's vice president? Jerry Lewis? [rushing out and down a hill toward his laboratory] Dr. Emmett Brown: I suppose Jane Wyman is the First Lady! Marty McFly: [following Doc] Whoa. Wait, Doc! Dr. Emmett Brown: And Jack Benny is secretary of the treasury. Marty McFly: [outside the lab door] Doc, you gotta listen to me. Dr. Emmett Brown: [opens the door to the lab] I've had enough practical jokes for one evening. Good night, future boy! [closes the door leaving Marty outside] Marty McFly: No, wait, Doc. Doc. The-the-the bruise on your head, I know how that happened. You told me the whole story. You were standing on your toilet and you were hanging a clock, and you fell and you hit your head on the sink. And that's when you came up with the idea for the flux capacitor, [somberly] Marty McFly: which is what makes time travel possible. [Doc opens the door and looks at Marty with a stunned look on his face]