Why ‘you’, not ‘they’?

Why ‘you’, not ‘they’?

The passage below is from The Catcher in the Rye by J.D. Salinger

I started giving the three witches at the next table the eye again. That is, the blonde one. The other two were strictly from hunger. I didn’t do it crudely, though. I just gave all three of them this very cool glance and all. What they did, though, the three of them, when I did it, they started giggling like morons. They probably thought I was too young to give anybody the once-over. That annoyed hell out of me — you’d’ve thought I wanted to marry them or something. I should’ve given them the freeze, after they did that, but the trouble was, I really felt like dancing.

In this paragraph, I don’t see why the underlined pronoun ‘you’ is used instead of ‘they’. The context before it suggests people who laughed are three women. Then the pronoun ‘you’ doesn’t seem proper to me. I know ‘you’ can be used to mean general people, that is ‘we’, as in You have to be 21 or over to buy alcohol in Florida. But this ‘you’ doesn’t seem to mean general people, either.

Could you help me out?

Thanks in advance.