"A Pain in the Ass" ("L'emmerdeur") was originally a play from Francis Veber--one of France's best writer/directors. The story was made into a film in 1973, remade as "Buddy, Buddy" in the States a few years later and now is remade here in 2008. In between, Veber also was responsible for "The Dinner Game" (recently remade as "Dinner for Schmucks"). These are a lot of films with essentially the same idea. In every case, a bad person ends up having their lives destroyed by an idiot--a well meaning idiot, but an idiot nonetheless.
The film begins with the police taking a witness across the country testify. However, there's a price on his head and the police are taking a caravan with several cars, an armored truck and lots of well-armed men. What they don't know is that an assassin is waiting across from the court in a hotel--waiting to pick off the witness. The problem is that a total idiot living next door starts a series of events that roll out of control when he attempts suicide. In addition, a guy who's stolen the idiot's wife gets pulled into it--and he, too, has his life ruined by the idiot and a lot of weird coincidences. It's all very dark--but also quite funny--even if it has been filmed many times already. While not among Veber's best work, it is still quite good--and I have no idea why it currently only have an IMDb score of 4.9--as this would seem to indicate it's a bad film.
