Bad Santa is great. Bad Santa 2, however… deary me.
Another vote for In Bruges, so funny and extremely dark and outstanding performances by all involved. I was just recommending it to someone the other day who was trying to decide if Colin Farrell was hot or not.
Trainspotting is another favorite- I used to have the VHS (that’s how old I am) and wore it out . The scene where Begbie blows smoke in Renton’s face is one of my favorites of all time.
Both films are so dialogue rich, you can’t get tired of them.
Yeah, they really should have just left it alone. But god forbid they leave a penny on the table. I just pretend this doesn’t exist.
I’ll toss in Tusk, a very, very, very bizarre film from Kevin Smith. You probably won’t like it, most people don’t. I’d compare it to a somewhat more lighthearted version of Human Centipede, though it may very well be somehow more disturbing.
Alec Guinness stars in this one.
This is a great film, and has a pretty amazing scene where Alec Guinness plays against 7 other copies of himself. Done before CGI was even conceived of…
good picks so far
Heh, or “Santa Sangre” or “Man Bites Dog”
aaaawwww-kwaaaarrrrrd (actually date for the latter rolled with it not too badly)
For delightful squirmfests, there’s Mike Leigh’s “Abigail’s Party”, featuring the most boorish couple, along with other dreary types, saying asinine things. Prattling to an extreme. His earlier “Nuts in May” has many “uncomfortable” moments that has, well, this viewer wildly enthused.
couple hospital ones -
Paddy Chayefsky’s “The Hospital” - George C Scott trying to keep it together in the demanding milieu of work and life.
Lars von Trier’s miniseries trilogy “The Kingdom”, of which I’ve seen only the first.
“Where Does It Hurt?” - more really a screwball flunk-out with Peter Sellars embarrassing hmself along with Marty Feldman and the worst theme song in all film history.
Though slotted more under horror, “Rosemary’s Baby” has oodles of great black humour and satirical references in it. While we’re with Polanski, “Cul de Sac” and “The Tenant” are absolute gems, definitely in my all-time top ten.
“Scenes From the Class Struggle in Beverly Hills” is fun. Any film showing a much taller Ed Begley Jr. intensely strangling a much shorter Wallace Shawn has got to be good, quality stuff.
Bob Roberts ( 
“They complain and complain, and complain and complain…” )
Has “American Psycho”, “Delicatessen”, “Fargo” or “The Producers” been mentioned yet?
“How to Get Ahead in Advertising”
I’m guessing “The Rutles: All You Need is Cash” would fall more under all that ‘mockumentary’ stuff.
“The Discreet Charm of the Bourgeoisie”
“The Cook, the Thief, His Wife and Her Lover”
“Fear and Loathng in Las Vegas”
“The Fourth Man” - probably filed under horror, but dark laughs galore (and dang hawt!)
I think so, I don’t think so, yes, and NO! I love the original Producers - Zero Mostel plays Max Bialystock as someone who had absolutely been shit on by life; I love Nathan Lane, but he had too much energy for Max. And Mathew Broderick couldn’t act his way out of a wet paper bag.
And I absolutely LOVED How To Get Ahead in Advertising. Another GREAT Handmade Film! You’ve got to love a movie with a killer zit. Handmade Films did some great bizaar movies.
How about “Man Bites Dog”? Mockumentary of a serial killer. Downright darkly hilarious, but fairly violent and sexual. Totally my kind of humor, though.
I just watched Netflix’s The Land (Kraj) a Polish anthology film that is a little bit difficult to describe. It’s kind of every-day types stores going bizarrely and sometimes horrifically awry. I recommend it if you want to watch something that is viewable in snippets, as this film is 6 separate stories that aren’t really tied together in any way other than theme and atmosphere.
Roger Corman’s Little Shop of Horrors is a classic that has become almost lost in the shadow of the musical adaptation.
Actually mentioned a couple times already (heh, including a former post of mine)
Withnail and I
more under the categorey of sci-fi, “Liquid Sky” has scads of black, twisted humour.
Man With the Screaming Brain
The Ruling Class
There’s Something About Mary
El Topo
Beerfest
Boogie Nights (technically a comedy-drama, but if you’ve seen it…)
If you have that on the list then you have to add Shakes the Clown as well.
Dammit. I swear I did a search! Must have forgotten to constrain it to the topic.
Funny you mention that, because I just now, for poops and giggles, did a seach on “There’s Something About Mary” - with no results.
Not the first time search hasn’t worked.
Ah yes, the Citizen Kane of alcoholic clown movies. 
I came here to suggest “Eating Raoul.” Finally saw it a couple years ago, TIVO’ed off TCM, and loved it!
If you’re really into dark comedies, try some of John Waters’ older stuff, and yes, I do recommend including “Pink Flamingos” on that list.
Brazil (The question you should ask yourself after viewing it is, when did he start being in the chair? My answer: He was never not in the chair.)
Kaleidoscope, a recent Netflix limited series. Dark and funny heist story.
Better Off Dead. I saw this when it first came out in 1985, and I think it deserves a watch every ten years or so. Source of many quotable lines.
Very Bad Things was one of my recommendations as well. Brutal.
To me, there’s been a drift on the question, and the context starts with the original mentioned film, Filth. It’s DARK, subject matter might offend. But it’s led to a bunch of offbeat comedies, or a bit dark stuff, which isn’t really the genre. I’ve seen most of those films, and they’d not make my list. Only Heathers and a couple here have been mentioned.
The topic DARK to me means paedophelia, extreme brutality, sexual perversion or suicide. The type of film which could also be described as Brutal. Much as I love these films, Fargo, Ruthless people and Shaun of the Dead, are gentle comedies in comparison.
To me, these are the list I’ve made, one might be an exception, and you’ve probably not seen it, but it is a DARK comedy nonetheless. Let’s start with three already mentioned:
Very Bad Things - Who’d have thought an accidental murder of a prostitute in Vegas could get MUCH worse?
Happiness - For the Maplewood bits alone. Can you actually make paedophelia funny?
Man Bites Dog - Not just a story of a camera crew following a serial killer, but in a world where other camera crews follow other serial killers, and the camera crews join in.
Now for the unmentioned:
Worlds Greatest Dad - I regard this as Robin Williams finest. A fathers horrible son kills himself in a sex accident, and he ends up writing his suicide notes to make him loved.
Season 7 - The contenders - In a Big Brother world, following the contenders who have to kill the others, last years winner is back in her home town with her lost love also a contender.
And I guess (and it’s not so good, because some of its segments aren’t so good), in the same genre as Filth, is The Acid House - another Irvine Welsh film of his novel, except it doesn’t quite capture his novel as well as others. Three stories, and one is more BRUTAL than the rest.
I love, “The Hitman’s Wife’s Bodyguard”. I’ve never seen mayhem, murder, parental betrayal, and the potential financial destruction of a continent presented in such a hilarious manner. LOL
Michael Gambon, who would go on to play Dumbledore, plays the thoroughly despicable mob boss Albert Spica. I remember the beginning scene, where he and his gang are kicking the shit out of somebody while his long-suffering wife is present. One of the gangsters starts to piss on the victim, and Spica slaps him, telling him “Don’t bloody urinate in public! There’s ladies present!”