Xander needed this party. He was SO not looking forward to the beginning of the school year. He'd barely made it through freshman year, a feat he would certainly have not have accomplished without the smartest girl in school as his best friend. He needed some fun before the torture began again.
Speaking of which, he hadn't seen Willow there yet and Jesse had found him and then immediately gone off to search for Cordelia. Xander didn't understand! One year of high school and suddenly, all Jesse could talk about was Cordelia this and Cordy that. If he thought magic existed he would have checked to see if the guy had been possessed. Willow had explained something about teenage guys and changing hormones and stuff, but Xander hadn't exactly paid that much attention. It wasn't like he was changing and chasing the bitchiest girl in school.
After being shoved away from the pool tables by some college guys when he'd grinned and asked if he could play a round, Xander stood by one of the tables, a cup of soda in hand as he watched the dance floor and contemplated joining the dancing crowd. So he did more flailing then dancing, the point was to have fun right? And fun the Xan-man would have, at the peril of other people's toes.
But first he was going to finish his soda and possibly have some hot wings.