The Trouble with Normal - Season 1 Episode 7 -

Claire advises the guys not to date anyone from the conspiracy convention they're going, trying to spare them from dating wackos. Claire's boyfriend, who she really thinks is a great guy, turns out to have a booth at the convention, and so Claire has to dump him because he's a wacko. Meanwhile, Bob is the only one who has the guts to tell Zack that he thinks his marriage is a mistake, and the two have a fight.