Um, nostalgia wave. It hits.
Remember before the "holy crap they're like fucking newlyweds line" in Episode 206? Where did Brian and Justin go after they left the table? They couldn't have left. They would've said goodbye or ran into Melanie and Lindsay if they were outside. Since they were practically necking at the table, I'd venture a guess and say upstairs to fuck. But, I'll take other guesses and gapfillers. :)