- What were you doing in there?
- What I was doing is a secret.

5 seconds sound clip from the Little Women (1950) classic radio play.

You can hear this line at 00:26:56 in the radio play.

Quote context

[...]

- Now you run along.

- But what'll I tell Laurie?

- Oh, tell him I went up in smoke.

- So Jo went into town. But what she didn't know was that Laurie went into town, too... and he waited for her in front of the publishing office.

- That's not very good manners, Mr. Laurence... following me.

- What about your manners? Trying to avoid me all the time.

- What were you doing in there?

- What I was doing is a secret.

- All right. Keep your secret. Only, I've got one, too.

- Oh? Something plummy?

- Something very plummy.

- Now, tell me yours... and I'll tell you mine.

- All right. Here.

- A bank draft?

- Well, read it.

[...]