It's like when I see a dancer I know at the mall, at a restaurant (near my home even) or out with their partner, etc, like at Friday the 13th. It would be wrong of me to ask for a dance...I say nothing...
If you see me in a strip club alone, then by all means come over and say hello. And Jimmy? Next time I pop into that club, make sure that dancer doesnt launch herself across the room.