Well, why don't you say it?
4 seconds sound clip from the It's a Wonderful Life (1946) movie soundboard.
You can hear this line at 00:24:46 in the Blu-ray version of the movie.
Quote context
[...]
- Let me hold that old wet dress of yours.
- Do I look as funny as you do?
- I guess I'm not quite the football type.
- You know, if it wasn't me talking, I'd say you were the prettiest girl in town.
- I don't know. Maybe I will say it.
- Eighteen? Why, it was only last year you were seventeen.
- Oh, no, no. Just right. Your age fits you.
[...]