They're your sisters too.
2 seconds sound clip from the Meet Me in St. Louis (1944) movie soundboard.
You can hear this line at 01:08:49.149 in the DVD version of the movie.
Quote context
[...]
- Esther, your ice cream is melting.
- Esther, is there anything wrong with you?
- Roses are red, John's name is Truett, Esther's in love and we always knew it.
- Mama, I refuse to stay here while my sister's humiliated by these ghastly children.
- Now stop it, you two, or up you go.
- Truett. Knew it. That's pretty good.
- I can't think of any word that rhymes with colonel. Unless it's infernal.
- I must say, it's very difficult for a person to have any private life in this family.
[...]