Act all suprised at first, then don't have sex with her for a week while I think about the matter.
Secretly get a castration during that time, something revesable.
Then say "if it's that important to you, lets have a baby".
We'll start fucking like rabbits, and of course; when I found out she was poking hole in my condoms I decided to break up with her. But first I'd need to fuck her boring.