Marty, please don't say that.
2 seconds sound clip from the Back to the Future Part III movie soundboard.
You can hear this line at 00:37:14.087 in the DVD version of the movie.
Quote context
[...]
- Here are the details for you. Thanks for all your help.
- Oh! Her name's Miss Clayton. Clara Clayton.
- Well, Doc, now we know who Clara is.
- Aw, come on, Doc. It's not science. You meet the right girl, it just hits you. It's like lightning.
- Marty, please don't say that.
- That's the way it was for me and Jennifer. I mean, we couldn't keep our eyes off each other.
- Don't worry, Marty. She'll be fine.
- When you burned the almanac in 1955, the normal timeline was restored.
- That means once we're back in 1985, you just have to go over to her house to wake her up.
[...]