You guys look great. Mom, you look so thin.
6 seconds sound clip from the Back to the Future movie soundboard.
You can hear this line at 01:47:59 in the Blu-ray version of the movie.
Quote context
[...]
- Yeah.
- I think we need a rematch, George. A rematch? Why? Were you cheating?
- No.
- Did you hit your head? Marty, are you all right?
- You guys look great. Mom, you look so thin.
[...]