You: Hey baby, do you know how much a polar bear weighs?
Her/Him: No, how much does a polar bear weigh?
You: Enough to break the ice. Hi I'm ________ <Insert name
That's how you tell it. This is how I would do it:
Me: Hey baby, do you know how much a polar bear weighs?
Her: No.
Me: Oh.
*Long awkward pause*
Me: That's enough beer for me. I'm going home.