- They don't know about us, do they?
- No. Why should they?

4 seconds sound clip from the The Philadelphia Story movie soundboard.

You can hear this line at 00:23:59 in the Blu-ray version of the movie.

Quote context

[...]

- You better go and tell them how terribly, terribly happy we are to have them.

- That's the old Quaker spirit, Mother Lord. Now, keep swinging.

- Oh. I thought it was that butler.

- The family will be down to welcome you in a moment.

- What with?

- With open arms.

- They're terribly, terribly happy to have any friends of Junius's here.

- They don't know about us, do they?

- No. Why should they?

- Look, our research department didn't give us much data.

- This fiancé of this girl, George Kittredge, age 32. You know him very well?

- Well enough.

- He's general manager of Quaker State Coal, controlling interest in the company owned by Seth Lord.

- That's the girl's father, huh?

- What a coincidence.

- How'd he meet her?

[...]