For people who dread seeing their relatives over the holidays, National Lampoon's Christmas Vacation is a comedy classic, but there's something at the core of the story that makes the whole thing seem more than a little sad. The fact that Clark Griswold (Chevy Chase) is a pretty terrible person is obvious from, well, pretty much every frame. The entire plot, after all, is driven by the fact that he's been spending money he doesn't have in an effort to be a big shot, and most of the comedy comes from the sheer, seething hatred that bleeds out in the form of one-liners at the expense of his extended family.

Unfortunately, that familial misery seems to extend to his marriage, too. When Clark heads to the store to buy a present for his wife, he encounters the beautiful Mary, and almost falls over himself with the desire to cheat on his wife. The fact that he's fantasizing isn't the problem — Nicolette Scorsese circa 1989 hiking up her skirt is enough to provide a distraction for a lot of people — but when his Freudian slip goes straight to "adultery," there's probably a bigger problem there.

Later, when he's fantasizing about how sweet life will be once he owns the pool, Mary shows up in his fantasy to do a swimsuit striptease on the diving board, which also involves all the relatives vanishing from both the pool and, presumably, his life — including Ellen. Again, the fantasy's understandable, but Clark mentally sorting Ellen into the same group as Cousin Eddie (whom he flat-out hates), is a pretty strong indicator that things aren't going well at the Griswold house. And that's before you remember that there's precedent for it — in the original Vacation, Clark goes skinny-dipping with Christie Brinkley after flirting with her on the highway, and is only stopped from cheating when he's interrupted by his wife.

And the worst part? Despite her happy face and the fact that she manages to keep it together through at least five movies, Ellen is absolutely aware of how much of a sham her marriage is. When her daughter complains about having to share a bed with her brother due to the family staying at the Griswold house, referring to it as "sick and twisted," Ellen's response is "Well, I have to sleep with your father." Yikes.