It's late October when I walk up to Mac DeMarco's home studio in Bushwick, Brooklyn, where the creaky iron gate outside never seems to shut all the way. The 23-year-old comes to the door looking and sounding like he's been up all night—eyes drooping, not really smiling. He's got a mustache and scraggly facial hair in that nebulous zone between “five o'clock shadow” and “actual beard.” He's wearing the hat he wears all the time, the one with the patch on it.

He points to a cluttered box of a room on the left, says it's his, and tells me to make myself at home while he takes a piss. In the hallway, there's a baby doll with demon wings hanging from the ceiling, twine tied around its torso. There's just enough clearance for his door to open, though sizable chunks of wood usually chip off whenever you close it. His room is maybe 15 feet long, and rumpled-up clothes and a five-piece drum kit take up at least 90% of the walkable floor space. He lives here with his girlfriend. There aren't any windows.

A month previous, after returning to New York from an extensive tour behind his breakout album 2, which included some arena gigs opening for Phoenix, DeMarco went to the store to stock up on everything he needed so he wouldn't have to leave this room. “And I pretty much haven't,” he says. Fruit flies hover around a full Viceroy-brand ashtray. For the past few weeks, he's been toiling on his third solo record in this space, recording every instrument on the record while chain smoking about two packs a day with the door closed. “In Canada, we call this ‘the Indian hot box,’” says DeMarco, who grew up in Edmonton. After four days of hanging out in the unventilated rectangle, my eye started twitching persistently; he calls this “smoker's eye.”

To understand why this grubby, gap-toothed kid has seized a strong following over the last few years, consider the other festival-friendly indie rock outfits currently in his sphere. In a heap of artists who take their craft very seriously, here's a guy with a penchant for public nudity, shameless drunkenness, and slovenly classic-rock covers peppered with the shouted words “SUCK MY DICK!” So while some find his behavior repugnant, others are enthralled with his youthful abandon; either way, within the often faceless world of modern guitar rock, DeMarco demands attention by not giving a fuck. It's no wonder he recently found a kindred spirit in shit-stirrer extraordinaire Tyler, the Creator, who tweeted: “DEAR MAC DEMARCO I LOVE YOU YOU ARE AWESOME.”

But DeMarco's not just some volatile loose cannon. There's a warmth and approachability about him; he recently covered Jonathan Richman live, and he talks about Steely Dan records with authority. His home-recorded love songs—near yacht rock-ian in their smoothness—contain widely universal sentiments. They're feel-good affairs performed with a deep-voiced croon and a warbly guitar tone that's distinctly his own. He's telling stories with a smile, crafting breezy songs that sound good at outdoor stages.

In person, he smiles and makes you feel like you're in on his jokes, however bizarre or disgusting they may be. He's the friend who actively looks for the party, drinks way too much when he gets there, and is eventually found passed out in the closet. He's an auteur with a lampshade on his head. A punk kid with moon eyes. An unwashed chain-smoker from the Canadian flatlands who keeps coughing between sentences.