1982 movie co-written, directed by, and starring Paul Bartel along with Mary Woronov as Paul and Mary Bland, an otherwise unassuming couple who has the unfortunate problem of having accidentally killed someone. They then realize the person was a swinger, and are disgusted, so they run fake personal ads in the paper, and when the swingers come over, they kill them. All the time, this quiet couple sees nothing wrong with what they're doing, because they're evil, filthy swingers anyway, so they're doing the world a favor. And keeping the money is just a side benefit.
That doesn't explain the movie's title, but let's just say there's a guy named Raoul (played by Star Trek: Voyager's Robert Beltran) and there's some interesting ideas about how to dispose of the bodies.
It's a really well done black comedy and worth seeing. It's sick but never seems to get overwhelming--it's just too absurd. Sadly, it's not out on DVD in the United States (but it is in Britain--damn you region codes!)