Eee, exo/endo! A guy I was dating once nearly broke up with me over an incident involving that. He was in college at UGA and was pretty much a loser. Anyway, he took me to some sort of professional group dinner (it might have been the ACM chapter's annual thing) as his trophy girlfriend. We were seated at a large banquet round with 10-12 other people, and I was making polite conversation while my date sat, sullen and uncommunicative. Someone at the table began telling me about his work, which was in epoxy formulation, and I leaned over and very sweetly (with full Southern flutter)said something like, "That's typically an exothermic reaction, isn't it?" So we began talking about some of the chemical conundrums he dealt with.

It turns out that the conversation infuriated my date, who felt that I was having it merely to make him look/feel stupid (which, alas, he was), and that a proper trophy girlfriend would have kept her mouth shut except for talking to or about *him*. He wanted me to apologize to him, or else.

I dumped him about a week later.