But then he would be lying.
4 seconds sound clip from the Labyrinth (1986) movie soundboard.
You can hear this line at 00:28:31 in the Blu-ray version of the movie.
Quote context
[...]
- Ooh. (2)
- How do you know? He could be telling the truth.
- So if you told me that he said yes, I know the answer is no.
- But I could be telling the truth.
- So if you told me that he said yes, I know the answer would still be no.
- Wait a minute. Is that right?
- I don't know. I've never understood it.
- No, it's right. I've figured it out.
[...]