Boss made poker joke?

Question

I work as a cashier and he was asking me if i received any cash yet since he opened up my register, and i said I havent got a twenty yet.

and he told me

Are we playing cards here sir?

that made me laugh but what card game is he talking about?

Answer 1

The one with your replacement's phone #

Answer 2

Black jack maybe.  An opening hand of 20 is almost as good as a 21 and happens a LOT more often.

Answer 3

poker probably.