I have the same impression everyone else does.... that it's more of a silly test, just to see how you handle it & react.
I've had several girlfriends over the years do the exact same thing. So what I did was make comments like:
"Oh yeah, he IS pretty good looking. If I decide to turn gay, he's TOTALLY mine!!"
OR "He's decent looking, but he's no Brad Pitt;... but then again, who is?"
Or "Oh yeah, you two would make such an adorable couple! But then you'd drive him crazy talking about how hot I AM & he'd end up leaving you."