"Humpday" is very interested in exploring this question. The film screens 8 p.m. Friday and Saturday at the Oklahoma City Museum of Art.

Ben (Mark Duplass, "The Puffy Chair") is a 30-something living the marital dream within a dream with Anna (newcomer Alycia Delmore). They own a house, have good jobs and are actively trying to reproduce. Then Andrew (Joshua Leonard, "The Blair Witch Project"), Ben's best friend from college, comes banging on the couple's door. Having just blown in from Mexico with no plans and nowhere to go, he crashes with Ben and Anna, upsetting their comfortable balance.

While Ben has chosen to settle down and grow roots, Andrew has been flaking out all over the place. During his first day in town, he meets a group of artists led by Monica (writer/director Lynn Shelton). Over drinks and doobies, someone mentions Humpfest, an amateur-porn contest sponsored by a local paper. All the cool artist types are participating, and so Ben and Andrew, in a bid for coolness, hatch an idea: Wouldn't two straight men having sex on film be a mind-blowing piece of art? Somehow?

Over the next couple of days, Andrew and Ben goad each other until they decide they're going through with the idea, if only just to prove to each other that they're still capable of doing something utterly impulsive, whether it even makes sense or not. Of course, Ben has to tell Anna what he's doing without triggering an automatic divorce.

While the movie's central idea really does sound like something a 14-year-old huffer would come up with, the execution makes all the difference. In the hands of a Hollywood director, "Humpday" would be filled with nonstop wiener jokes and sight gags, and would likely leave anyone with an IQ over 80 feeling in need of a hot shower.

But what Shelton seems to be aiming for is an illustration of the differences between kinds of love. There's the conventional, recognizable love between Ben and Anna, and there's the love between Monica and her girlfriend (newcomer Trina Willard), each of which is legitimate, despite their flaws and complications.

And then there's the platonic man-love between Ben and Andrew, which is also complicated and real. The point seems to be that sex is inextricably tied up with love in one way or another. But it doesn't necessarily follow that love makes sex possible, and watching two straight guys try to get it on is like watching a lion trying to figure the slope of a line.

Despite its boneheaded premise, "Humpday" contains some well-written, funny material and genuine moments, and actually manages to convey a fair bit of emotional complexity.