Because no man can be friends with a woman that he finds attractive. He always wants to have sex with her.

Harry Burns (Billy Crystal)

6 seconds sound clip from the When Harry Met Sally... movie soundboard.

You can hear this line at 00:12:31 in the Blu-ray version of the movie.

Quote context

[...]

- You only think you do.

- You're saying I'm having sex with these men without my knowledge?

- No, what I'm saying is they all wanna have sex with you.

- They do not.

- Do, too.

- They do not.

- Do, too.

- How do you know?

- Because no man can be friends with a woman that he finds attractive. He always wants to have sex with her.

- So you're saying that a man can be friends with a woman he finds unattractive.

- No, you pretty much wanna nail them, too.

- What if they don't wanna have sex with you?

- Doesn't matter. Because the sex thing is already out there, so the friendship is ultimately doomed, and that's the end of the story.

[...]