The "Gamekillers" are a collection of stereotyped characters who represent certain personalities who, according to Axe and the show's producers, teens and 20-somethings often encounter throughout the course of their social life. In particular, each Gamekiller is said to be particularly skilled at inadvertently—or sometimes purposely—ruining a date and breaking up a couple.
The reason that I mention this is that Allyson might have an excellent reason for thinking that Gordon is a doofus that she can't waste her time with. Not only is he flanked by Peter "The Baller" Kent who uses his sports prowess to kill his game, he's also associated with Mike "The Mess" Patterson: "A guy who is not only a slob, but tries to provoke immaturity from his friends."
Allyson, you see, has something called a memory. Allyson remembers that some idiot got his stupid self talked into shoving his fool head into a hole in the girls' shower at camp. She also remembers that said moron made a big production of screaming about the 'cruelty' of Martha McRae not following some silly note protocol because he thought that he was in third grade and the guys would tell him he had cooties if they know he had a girlfriend. Soon, she's going to know that she didn't have to get sick on homebrew at all but Mike talked Gordon out of stopping things because he wanted a stupid spectacle. This means that she thinks that Gordon's association with a childish goof means that he's not worth her time.