How to negotiate price like a man ... and like it

So I'm standing in a furniture store where, after two months of searching, I have finally found a sleeper sofa that a) fits

my space, budget and style; b) has passed my official Sitz Test; and c) doesn't feel like a Medieval torture device. What's more, I can also buy the Tempur-Pedic mattress I want for the bedroom at the same store. Perfect. Done. When can you deliver?

Then my father speaks up. I don't mean figuratively, like when you hear yourself saying, "Close the door. We're not trying to heat the neighborhood," and you suddenly realize you've become your parent. No, my father is actually standing there, shopping with me. And this is what he says to the salesman:

"What can you do for us on price?"