I'm sorry. I have an engagement.
4 seconds sound clip from the The Roaring Twenties (1939) movie soundboard.
You can hear this line at 00:36:25 in the DVD version of the movie.
Quote context
[...]
- Oh, yes, I remember. You haven't changed a bit.
- You have. Three years make a big difference.
- Yes, my character has changed, hasn't it?
- Well, excuse me. I have to change.
- Will I see you after the show?
- I'm sorry. I have an engagement.
[...]