Only party I'll be smiling at is the one that sees you at the end of a rope.
5 seconds sound clip from the Back to the Future Part III movie soundboard.
You can hear this line at 00:55:49.396 in the DVD version of the movie.
Quote context
[...]
- Just like you, Tannen, I take every advantage I can get.
- Now you gonna check your iron?
- Smile, Marshal. After all, this is a party.
- Only party I'll be smiling at is the one that sees you at the end of a rope.
- Why, Mr. Eastwood, nice to see you.
- I see you got yourself some respectable clothes, lad, and a fine hat.
- Yeah, well, a couple people didn't like the way the other one looked on me.
[...]