There's always one, and this year's throw-down-the-gauntlet gut-churner was The Human Centipede, about an insane surgeon who kidnaps test subjects and grafts them into fleshy chain, mouth to anus.
It's a truly horrific (and therefore inspired) concept, especially when you pause to think it through. That's right: the first in the chain must 'feed' the second, and so forth, until the recycled waste finally comes out the far end.
As Stephen King says, there are three levels to horror: terror, horror, gross-out, and if you can't achieve the first you go for the second, then the third - whatever it takes to punch out that reaction.
Interestingly, though, The Human Centipede is not what it's cracked up to be.
Firstly, it is not, actually, nearly as vomit-inducing and the hype suggests. Far from being this year's Irreversible, Martyrs or Inside, films that push boundaries, it is (relatively speaking) a rather tame affair.
Perhaps showing surprise restraint, certainly trusting that the concept takes things far enough all on its own, director Tom Six holds back from showing too much detail. Rather ridiculously, those in the human centipede are allowed to keep their underwear on, plus bandages, thus preserving some sort of modesty even when shuffling around the garden sucking arse.
Six would argue that it is to protect their scars - a quote on the poster proclaims the film '100% medically accurate' (!) - but it's really no different to watching Julia Roberts receive CPR with her bra still on in Flatliners.
Centipede is a black comedy, which is perhaps the most shocking thing about it. Those hoping for clinically delivered carnage of the sort Cronenberg or Haneke excel at will be sorely disappointed, as evidenced the moment we meet our arch villain, Dr Josef Heiter (Dieter Laser), leafing through photos of his three-dog. Six is more interested in eliciting wry sniggers than dry heaves.
Unfortunately, his movie is also not what it's cracked up to be in terms of quality. Expected to be one of the stand-outs of FrightFest, it instead proved itself to be a slow-moving, repetitive affair that has nowhere left to go by the hour mark.
After all, once you've captured your subjects and done the science and they're now shambling across the living room floor, fetching a newspaper like a centi-dog, the story's done. The second half descends into formula as the cops come a-sniffing.
It also doesn't help that Laser is something of a pantomime villain (and a knowing nod to the distinguished chain of mad movie scientists), all bulging eyes under dark glasses.
Still, The Human Centipede is one of those films you have to see just to say you have. The concept remains robust no matter how many times you poke at it and the film has several scenes (all in the first hour) that come close to delivering on it.
If it finally emerges a disappointment it's because the hype machine is a far bigger beast than Six - at least until the planned sequel when the centipede will grow in length and Six, inevitably, will have to pull out all stops to exceed his original.