- I noticed your little pin there. That's like a signal, isn't it?
- Sort of.
- A signal. A secret signal for a Secret Service.

10 seconds sound clip from the Taxi Driver (1976) movie soundboard.

You can hear this line at 01:03:49 in the Blu-ray version of the movie.

Quote context

[...]

- They were just here. They were very, very...

- Suspicious.

- Yeah.

- Where'd he go?

- Is it hard to get to be in the Secret Service?

- Why?

- Well, I was just curious, because I think I'd be good at it. I'm very observant.

- I was in the Marine Corps, you know.

- I'm good with crowds.

- I noticed your little pin there. That's like a signal, isn't it?

- Sort of.

- A signal. A secret signal for a Secret Service.

- Hey, what kind of guns you guys carry? .38s? .45s? .357 Magnums? Something bigger, maybe?

- Look, if you're really interested, if you give me your name and address, we'll send you all the information on how to apply. How's that?

- You will?

- Sure.

- Okay. Why not?

- My name is Henry... Krinkle. K-R-l-N-K-L-E. 154 Hopper Avenue.

[...]