Don't know if she was on the bar, or the stage next to the bar, given the configuration of Carlos & Charlie's.
In certain "party bars" they encourage people, especially attractive young women, to get up and dance on the bar. It enhances the whole "out of control" partying atmosphere.
in the pic at post 1139, she is clearly standing on the floor, because her left shoulder is obscured by the seatback of a barstool