A teen pregnancy goes horribly awry in Snatchers, a charming genre-bending send-up of B-movie creature features, infused with the anything-goes spontaneity of sketch comedy. The horror/comedy debuted last weekend at the SXSW Film Festival in Austin, Texas.

(Mild spoilers for Snatchers below.)

High school student Sara (Mary Nepi) is pretty and popular, but she's also just been dumped by her hunky boyfriend, Skyler (Austin Fryberger) because she wanted to wait to have sex. He tells her he's "changed" during his trip to Mexico over the summer and now has "different priorities"—essentially he's turned into a mass of teenage hormones seeking any outlet for release. Desperate to hang onto her social status, Sara relents to his advances, but they don't use protection. She wakes up a day later not just pregnant, but fully nine months pregnant. And what she's carrying is definitely not a baby but some parasitic alien creature that shoots out from her uterus like a bloody cannonball. Things just get weirder (and gorier) from there.

Co-directors Stephen Cedars and Benji Kleiman are childhood friends with a shared love of movies and movie-making, especially the films of Steven Spielberg, Sam Raimi, Edgar Wright, and the Coen brothers. They started doing sketch comedy and improv in college and found audiences responded best to sketches that told a story of some kind. Storytelling also proved a natural fit for their love of genre.

"Genre tropes [are great] for setting up comedy expectations because everyone knows how certain moments in certain genres work," said Cedars. "Subverting those conventions is how you generate a lot of comedy."

“We knew we wanted to tell a story about a person getting pregnant with an alien.”

"When you make an audience so invested in the story they forget there might be another joke coming, that's how those magic moments happen," said Kleiman. "Making those sketches really did shape how we viewed the ability to set an audience up and then twist them when we wanted to."

Snatchers started out as a short film at SXSW a few years ago before becoming a series on Verizon's short-lived go90 app. But co-creators Cedars, Kleiman, and Scott Yacyshyn (known collectively as The Olde Money Boyz) always intended it to be a feature-length film. "We knew we wanted to tell a story about a person getting pregnant with an alien," said Cedars, and everything else developed from there. It's described in the promotional materials as Mean Girls meets Shaun of the Dead, but true fans of sci-fi monster movies will also detect notes of Gremlins, Species, the larval facehuggers from the Alien franchise, and similar fare. The homage is not always deliberate, either. Watch enough monster movies and you'll start to absorb those influences through osmosis.

The creature's biology is remarkably credible for a fictional alien pregnancy monster, especially its development cycle. That was no accident, according to Kleiman.

"We really wanted the only leap in logic to be that [the alien's development] progresses so quickly, but we wanted all of the biology to make at least a semblance of sense," he said. "So we looked at wasps and other parasitic creatures to figure out what a morphological life cycle would look like."

Without giving too much away, the creature hacks the central nervous system by attaching itself to the back of a human neck. ("Sir, are you aware there's a lobster on your neck?" a bemused policeman asks one of the snatched hosts.) This enables it to control the host's body—much like those parasitic wasp larvae that turn unsuspecting ants into their zombie slaves.

Snatcher's success really rests on the young shoulders of its two leads, Nepi and Gabrielle Elyse as Sara's nerdy ex-BFF Hayley, who goes above and beyond the call of duty to help her estranged pal.

The writers worked hard to avoid dialogue that sounds like 30-something men trying to imitate the language of teenaged girls. Cedars even contacted a local high school at one point asking if he could come and observe the students' speech patterns for a day—he was flatly turned down. Only then did he realize the request was doomed to come off as creepy.

One thing Snatchers is not is a teen morality play in disguise, despite the possible metaphor of an STD (any girl Skyler beds is bound to become infected). Sure, Sara has sex and pays some consequences, but she blithely brushes aside all attempts to shame her—a refreshing stance for the genre.

"Horror has a long history of using sex as a taboo that gets violated and is punishable," said Cedars. "We wanted to make sure we weren't treating sex as a bad thing. We're both very pro-sex. It wasn't the sex that was [Sara's] mistake—it was having sex for the wrong reasons," i.e., to be popular.

The duo is already hard at work on their next film, although all Kleiman will say about it is that it combines comedy with a David Cronenberg-esque "body horror" sensibility. We're betting they'll pull it off.