Marty McFly: Whoa. Wait a minute, Doc. Are you trying to tell me that my mother has got the hots for me? Dr. Emmett Brown: Precisely. Marty McFly: Whoa. This is heavy. Dr. Emmett Brown: There's that word again. "Heavy." Why are things so heavy in the future? Is there a problem with the Earth's gravitational pull?Or
George McFly: Lorraine. My density has brought me to you. Lorraine Baines: What? George McFly: Oh. What I meant to say was... Lorraine Baines: Wait a minute. Don't I know you from somewhere? George McFly: Yes. Yes. I'm George. George McFly. I'm your density. I mean, your destiny.These illustrate my point that the jokes are firmly planted in the Zemeckis/Gale universe and nail it. Others like when Marty orders a tab at the 1950s coffee shop is still funny but as the TAB soda company continues to fall out of the general consciousness, that joke is gets more difficult to get. Do the jokes hold up? Yes, at least the ones that inhabit the universe.