- Why are you so nervous?
- You got a guilty conscience?
- No! Why should I?

4 seconds sound clip from the The Little Shop of Horrors (1960) movie soundboard.

You can hear this line at 00:43:03.009 in the Blu-ray version of the movie.

Quote context

[...]

- Look at my plant!

- I'm looking.

- Your name Gravis Mushnick?

- Mushnick, Gravis. That's my name.

- Just want to ask you a few questions.

- Questions, ask me.

- Just want to ask you a few questions.

- I didn't do it.

- Do what?

- Whatever.

- Ever see this man?

- Man see picture...

- Why are you so nervous?

- You got a guilty conscience?

- No! Why should I?

- Ever see this man?

- Man see this picture... Dr. Farb.

- So you know him?

- He's my dentist.

- He maybe did something?

- He disappeared.

- Blood in his office.

- The other man, too. Blood in the railroad tracks.

- And a few spare parts.

- Dr. Farb is murdered?

- Is he?

- Who knows? Not me!

[...]