Cameron Diaz and Jason Segel meet in college, fuck a lot, then get married and the fucking goes bye bye. So one night they light the fire by making a sex tape, and then it gets out. The rest of the movie is about them trying to get it back.
Funny, but really stupid film.
I will say that the opening 10-15 minutes is the most realistic depiction of marriage I've seen in a movie. Think first 5 minutes of Idiocracy reality.
Aside from the honesty of the beginning, the movie is really, really, really dumb, but there are laughs. Creepy Rob Lowe shows up for a bit, as does another celeb late in the film.
Worth a single viewing for some chuckles and Cameron Diaz showing more skin then ever, however be warned that Segel is naked as usual.