You know, you meet a new girl, you are pretty sure she's single, then you drop the bomb and out comes the truth:

"I'm sorry, I already have a boyfriend"

At this point I look like a deer caught in the headlights. I was able to once play it off by saying "Oh, i'm sorry for you loss" and walked away from the car but I don't think that was too slick. I wanna know, what are you best comebacks for that situation?