Daisy Buchanan: Rich girls don't marry poor boys.
Jay Gatsby: How do you do, old sport? I'm Gatsby.
Nick Carraway: They say you killed a man.
Jay Gatsby: Only one?
Jay Gatsby: Klipspringer has been here since a party I threw in April. I didn't even realise he was here until two weeks ago.
Daisy Buchanan: And when I was in the delivery room, waking up from the ether, I asked the nurse whether it was a boy or a girl. She said it was a girl - and I turned my head to the side and cried. And then I said, I hope she grows up to be a pretty little fool. That's about the best a girl can hope for these days, to be a pretty little fool.
Answer: He wants to impress Daisy by showing authority and control.