Wait a minute, Doc, are you trying to tell me that my mother has got the hots for me?

Marty McFly: Wait a minute, Doc, are you trying to tell me that my mother has got the hots for me?
Dr. Emmet Brown: Precisely.
Marty McFly: Wow, this is heavy.
Dr. Emmet 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?