No clues except your well-known calling card.

3 seconds sound clip from the The Return of the Pink Panther (1975) movie soundboard.

You can hear this line at 00:38:49.169 in the Blu-ray version of the movie.

Quote context

[...]

- Four years ago I swore to you that I was retired.

- I've been faithful to you ever since.

- In your fashion.

- What the hell does that mean?

- That you're being teased.

- I believe you, darling.

- But you must admit it does sound like the kind of job only the Phantom could have done. I mean, the Pink Panther.

- No clues except your well-known calling card.

- Yes, I must admit the impostor... Very clever. Very clever, indeed.

- I'm surprised that half the police force of France hasn't descended on us by now.

- But of course they will.

- Without a doubt.

- But if you're innocent?

- Look, darling, I'm not only innocent, but I'm still smart enough that if I decided to get back in the business, I would not leave my calling card announcing the fact.

- No, but will the police think of that?

- No.

- But you can convince them.

[...]