Which movie really shouldn't have been as good as it was?

The kind of movie that on paper seems like it would probably not work or not work as well as it actually ended up doing, given the cast, budget, etc.

One I think of, from many years ago, is Office Space. It eventually became popular and developed a cult following but it could have remained the failure that it had been at the box office. I mean it was a movie that didn't have many big names, and was about boring paperwork and about guys in cubicles hating their jobs and a guy obsessed with a red stapler. It should have bored you to tears.

But the movie was very funny and people who've worked in cubicles and hated their jobs realized this movie really got it, really captured what it was like they were dealing with everyday and watching it was so cathartic. And still remains one of the funniest work-related movies. So that's the one that has my vote.