You're just low enough to think of something like that.
4 seconds sound clip from the Gone with the Wind (1939) movie soundboard.
You can hear this line at 03:02:33 in the Blu-ray version of the movie.
Quote context
[...]
- Yes?
- You see... Well, I've decided... Well, I hope I don't have any more children.
- No, but you know what I... Do you know what I mean?
- I do. And do you know I can divorce you for this?
- You're just low enough to think of something like that.
- If you had any chivalry in you, or or would be nice, like...
- Well, look at Ashley Wilkes. Melanie can't have any more children and he...
- You've been to the lumber office this afternoon, haven't you?
- What has that got to do with it?
- Quite the little gentleman, Ashley.
[...]