Marty McFly: [watching a Honeymooners episode in 1955] Hey, hey, I've seen this one. I've seen this one. This is a classic. This is, uh, where Ralph dresses up as a man from space.
Milton Baines: What do you mean, you've seen this? It's brand new.
Marty McFly: Yeah, well, I saw it on a
[realizing]
Marty McFly: ... rerun.
Milton Baines: What's a rerun?
Marty McFly: You'll find out.