Available on DVD: “Jeff, Who Lives At Home”

Jeff, Who Lives at Home, with Jason Segel as the 30-year-old title character — a stoner, a slacker, a guy who can hardly get dressed, let alone get a job — begins with a monologue about the genius of M. Night Shyamalan’s Signs.

Clutching a tape recorder, Segel’s Jeff Thomkins ruminates about the significance of the 2002 Mel Gibson/Joaquin Phoenix movie, its themes of fate and portent, and how every little thing leads to this one significant, synchronicitous moment.

Nothing in this quiet, quirky comedy from the brothers Duplass (writer-directors Jay and Mark) comes close to Jeff’s inspired, bong-fueled deconstruction of Signs, but it gives us a good idea of where this guy is coming from. And why an errant phone call isn’t merely a wrong number, but a clue to something more meaningful, perhaps even life-changing.

So Jeff lives in the basement of his mom’s house, safe from the blinding light of the streets of Baton Rouge. His mother (Susan Sarandon) has a real job, and a real ache of loneliness. It’s her birthday, and all she wants is for her son to put on some clothes and take a bus to the hardware store to buy some wood glue. Is that too much to ask?

Apparently, yes.

And then there’s Jeff’s brother, Pat (Ed Helms), who is clueless in a more proactive way. He goes out and buys a Porsche, even as his wife, Linda (the great Judy Greer), says they can’t afford it. And when Jeff and Pat run into each other later that day, they spy Linda having what looks like a romantic assignation. Jeff is put on the case to find out what’s going on, eavesdropping from an adjacent booth in a restaurant, like some pothead sleuth.

Jeff, Who Lives at Home is shambling and talky, in the manner of the Duplasses’ The Puffy Chair and Cyrus. An irritatingly cute marimba-driven score runs throughout, trying to wring poignancy out of the awkwardness, à la Miranda July. And maybe it’s the Louisiana locale and the high loser quotient of its cast of characters, but the film is remindful, too, of a Frederick Barthelme short story. People lead sad lives, do peculiar or self-destructive things, and then a strange happenstance — or, in Jeff’s eyes, a twist of fate — transpires.

Like Jeff’s rap about Signs, the Duplasses’ screenplay builds to a "perfect moment," where all the seemingly random clues Jeff has been discerning coalesce in an a-ha! moment of considerable import.

The plausibility of the finale is open to question, but the filmmaking duo’s determination to take us there makes a nice kind of sense.