With “A Dirty Shame,” John Waters delivers good-natured debauchery in his signature B-movie package.

Similar to a really entertaining “Saturday Night Live” sketch, the film provides easy laughs without any emotional attachment required. Sylvia Stickles (played by the venerable British personality chameleon Tracy Ullman) is a prudish resident of a middle-class suburb of Baltimore. Repulsed by all things sexual, including her mild-mannered husband Vaughn (Chris Isaak), Sylvia has padlocked her libido-crazed, exhibitionist daughter (Selma Blair) in her room. Extreme for any teenager, Caprice, who has forgone the usual-sized boob job in favor of something around the size of birthday balloons, is interested only in sex and to that end has quite a following at a trucker bar downtown.

On her way to work one day, Sylvia receives a bad concussion during a car accident that knocks her unconscious. Luckily, a mechanic named Ray-Ray (Johnny Knoxville) is there to check under her hood. After administering cunnilingus to the passive Sylvia, Ray-Ray reveals all. No ordinary serviceman, he describes himself as an apostle of sex and requests Sylvia’s help to reach the resur-“sex”-tion. Although this might seem overwhelming to most, Sylvia, turned sex addict from her head injury, quickly comes to terms with her new role while being introduced to fetishes galore along the way. Eventually joining up with Caprice, Sylvia must take on her role as the twelfth apostle and face off against her battle-axe of a mother, Big Ethel (Suzanne Shepherd), in her quest for the ultimate release.

For an NC-17 movie about sex in which the actors are mostly needed for their organs, it is ironic that the funniest moments come from the waist up. Waters is a master of casting slightly odd-looking people who would never be given a second glance in real life but in front of the camera are fascinating to watch. The disjunction between these people’s familiar everydayness and the foul words coming out of their mouths is a form of humor that glamorous Hollywood stars are not able to pull off. This smart casting contributes significantly to the best scene in the film, and one of the funniest in recent cinema, involving a water bottle and the Hokey Pokey.

The other highlight of the film is more familiar but equally good. Just listening to Johnny Knoxville preach sexual healing is funny enough, but the faces he makes — ranging from ecstasy to fanatical determination — push his performance into a no-man’s-land between pure farce and believability. He takes himself so seriously that by the end of the film it seems plausible that Ray-Ray has some sort of power over the miraculous.

“A Dirty Shame” abounds with perverse imagery. From a tongue coming out of a paper towel roll to a finger thrusting in and out of chopped meat, sex is literally on display everywhere. Eventually even the trees get involved, springing to turgidity and lewdly showing off their knotholes.

The dialogue is even less subtle. Not all the verbal jokes are entertaining — some are just plain disgusting — but most hit their mark with hilarious abandon. References fly out from every direction, as at a 12-step meeting when a reformed Sylvia refers to her nether region as “the axis of evil.” Through it all, it is the outright outrageousness of Water’s “anything goes” style that drives the humor.

Playing at York Square and with a compact running time of 84 minutes, “A Dirty Shame” is a fun study break that doesn’t put any intellectual pressure on its viewers. It’s not Stoppard, but it works.