Man, I'm getting a hell of a lot of google hits from people searching for Something Positive Nancy. Which just goes to show that I'm not the only one who was confused by Milholland's pulling an obscure background character out of his hat. In any case, sit and stay for a while! This isn't a Something Positive blog, or even primarily a webcomics blog, but maybe you'll find something interesting. Feel free to comment.
Also, Nancy is one of Aubrey's girls from Nerdrotica. She first showed up in the Class of Ninety-Bore storyline, when she was one of the girls Jason brought down to help Davan show up his classmates. You'll note that in that storyline they hit it off, but it didn't go anywhere until now. Since then there have been a few mentions of her, for instance in the series around when Episode 3 came out Aubrey mentions her being the first one to get her alien request form in. Further, if you look at the post-its on Davan's desk from when he was working at the insurance company, they all say "Nancy Called," indicating that Nancy's been trying to contact him a lot and, until now, he hasn't reciprocated. Hope this helps!