Is it ok to sleep with a girl the first time meeting her?

I met a girl last night at a bar from a friend. My friend gave her a ride home but he parked up, and I started makin out with her. Than she climbs on top of me and whispers I wanna f***. but we didn't cause my boy was in the front seat with his girl. Would it have been ok if I did. This girl was cute but she wasn't the type to take home..I'm 21.