Do girls like it when you call them my girl?

some do and some don't, it's down to the girl.

In the same way that you may or may not like it if a girl called you 'my guy'.

I assume girls would be most comfortable being called your girl if you were in a relationship with them, which may make girls that you're not in a relationship with that you call 'my girl' feel a bit weird because, they're not 'your girl' if you see what I mean.

but as I said before, each to their own.