“China Illinois” begins with gentle giant Mark “Baby” Cakes in his usual mode, telling stories to his diary in his customarily idiosyncratic way. “Dear diary,” he says, “today me and Dad tried to clean our insides out, with plant hairs, tree ejaculates, and leafy-weafs.” “Tree ejaculates” are, of course, Baby Cakes’ unique way of saying “fruit,” just one of many phrases this character has coined that should obviously become part of the standard English lexicon immediately, for the sake of a more interesting future. When the unsatisfying meal is done, Baby Cakes comes upon “a lonely little pursey, with a pink diary hanging out,” completely failing to notice the bloody car accident adjacent to the lost purse.

The plot thickens when it is revealed that the owner of the purse was a professor at the local community college Baby Cakes attends, and that she was in an unhappy relationship with the self-absorbed Professor Frank, who romantically proclaimed to her, “You’ll never want to be anything more than the thing I am in.” Like his forbidden romance with his Dad’s girlfriend in “Baby Cakes Diary #4,” Baby Cakes becomes furious with Frank’s poor treatment of his newfound beloved, only to ultimately reconcile his feelings in a typically strange way by the end of the series.

Both Baby Cakes and Professor Frank are prone to expressing themselves through song, which, along with Baby Cakes’ poetic wordplay, brings an odd poignancy to an otherwise silly and very funny series. It’s surprising that an animatic cartoon that refers to Helen Keller as “history’s most famous little caca-faced animal kid” can strike deeper chords about the meaning of life, but that is a special ability Neely shares with fellow crude animation genius Don Hertzfeldt, and it is what makes “China Illinois” such an enduring creation.

The series focuses on six strangers brought together in the seemingly posh house for the sole purpose of having sex with one another. Each of them is a conveniently pegged type: Jay (Boyd Harris) is described as a “bro,” a “trim-seeker” and a “sex lover,” and his personality would not be out of place on “Jersey Shore”; Jay’s obvious female counterpart, Tara (Ashley Lobo), is a “sorority princess,” “proud skank” and “maneater”; Erin (Fiona Robert), an 18-year-old virgin, is “naive,” “clueless” “jailbait,” while Alex (Lea Pascal) is an “alt-punk” “polysexual princess”; Derek (Chris Boykin) is the show’s only gay guy, so he is described as a “sexually promiscuous” “flamboyant fireball,” but the show’s real wild card is Frank (Jesse Dabson), a 45-year-old “big daddy” who won a Tombstone pizza contest to get on the show.

The first few episodes progress as might be expected, with the desperate Alex trying to have sex with anyone and everyone, while Jay admits that “Tara’s pretty slutty, I get it,” though he is more interested in deflowering Erin, who is “totally smokin’. I’m like, ‘I’m tryin’ to have sex with that!’” The gang plays a disastrous game of “Sexy Truth or Sexy Dare” and receives pole dancing instructions in the third episode, “Get on That Pole!” Meanwhile, the males are given some “bro lessons” by Danny Vullmer (Chris Meister), a hacky comedian who makes dated references to Urkel, En Vogue and Roseanne Barr. Things get more and more disturbing after that, as “Erin Bares It All” in the fourth episode with a shocking announcement that changes everything, and the show’s participants begin to revolt against its creators, including the “asexual” and very creepy host (Chris Agos).

In its most recent episodes, “Sex House” has gradually become more like a horror film, which only makes it funnier, beginning with the disgusting “Banana Sex Olympics” in episode 5 and continuing with “Dr. Sex” in episode 6. By the most recent episode, “Sex in a Bottle,” things are looking decidedly grim for the malnourished prisoners of Sex House, and the preview for episode 8 (which goes live today) makes it clear that it’s only going to get worse. New episodes go live every Thursday on The Onion’s YouTube channel.