It's a slasher movie made maybe in the 70's about 3 guys, 1 fat guy and 2 skinny guys.
They terrorize a town by knocking on doors of people and then beating them with bats and hammers when they opean the doors.
They do this while wearing clown costumes or clown masks. I remember there was this grusesome rape scene they have with one of their victims that made this movie very controversial.
I belive they had a british accent so this movie might be british. When they beat their victims a very distinctive circus song plays. At the end the 2 skinny guys try to drown the fat guy in a boat dock type place.
I hope this rings a bell. This movie is a gruseome classic and I want to watch it this weekend. Reps for the name.