She's just kidding.
4 seconds sound clip from the The Roaring Twenties (1939) movie soundboard.
You can hear this line at 00:47:29 in the DVD version of the movie.
Quote context
[...]
- I don't expect to get a sucker like you every night.
- Don't you ever say that to me again, do you hear? Never.
- Swell.
- Shouldn't have told me that, chump. That'll be 10 bucks extra on your check.
- Well, she goes on in a couple of minutes.
- Panama, I'll let you in on something.
[...]