On “Troglodyte”, the lead single from Viagra Boys’ upcoming album Cave World, frontman Sebastian Murphy sings about an incel who dreams of becoming a shooter. “He says he don't believe in science/ He thinks that all the news is fake,” he cries out, before dialling back the clock to pre-human times “when we had hairy arms and legs/ And you were still swimming round in a lake”. It’s the sort of esoteric online content that you see strewn across the manosphere via Jordan Peterson videos and 4chan, with references to everything from Return to Monkee to dinocore.

“The song has a bunch of timeline errors, because when I first started writing it, I thought a troglodyte was one of those fossils you find in a rock,” Murphy confesses. “I was referencing someone being so far backwards that they’re a fucking seashell, like the most primitive form of life. But then, I realised that I was completely wrong, and a troglodyte is a fucking caveman.”

He’s speaking backstage at Primavera festival the morning after a particularly rough night for the Stockholm singer, who has the vacant stare of someone who’s seen better days – “I’m so hungover,” he says, with a sigh. Sitting on a bench beside a row of toilet stalls – a strangely fitting context given the singer’s louche on-stage persona – he holds a can of beer in one hand and a tin of snus in the other. “I like internet culture and I watch a lot of YouTube and knowing where memes come from,” he begins. “I saw this really interesting documentary about the cognitive trade-off hypothesis, which shows how monkeys have really good short-term memories that we don’t have. It made me think about the whole world in general, like how people fucking suck.”

Cave World, the Swedish band’s darkly comic third album, is the result of a pandemics-worth of scrolling. With mentions of conspiracy theorists and anti-vaxxers, it is, in many ways, a reflection of society at present, packaged in Murphy’s instantly recognisable strain of debauched post-punk. “I think there’s a lot of inspiration just from the downfall of society and what’s been going on in the world recently and the divide between people and the extremely polar opposite ideas of how the world should be – and just this general feeling of chaos and destruction,” he explains.

For bands like Viagra Boys, whose values are progressive but whose presentation is terminally sleazed-out, it’s hard to discern what’s a parody and what’s not. Ever since the release of their 2018 debut Street Worms, the band have made a reputation for skirting the boundaries of political correctness, whether that’s lampooning toxic masculinity while playing into machismo stereotypes, or reflecting on themes of classism on their chaotically exhilarating sophomore album Welfare Jazz. Even the band’s name is subject to controversy: ‘Viagra’ is routinely replaced with ‘V**gra’ to avoid PR emails landing in spam.

A natural-born frontman, Murphy, too, takes on the role of the anti-hero, with self-aware lyrics often alluding to his own dickish behaviour. On “Ain’t No Thief”, for example, Murphy rebuts someone who is accusing him of stealing their jacket (“I ain’t no thief/ We just happen to have the same stuff, motherfucker,” he spits), while on “Punk Rock Loser”, he insists that he’s “looser than a piece of low-hanging fruit” against a rollicking array of outlaw country rhythms (Murphy, a tattoo artist by-day, has the word “LÖS” – meaning ‘loose’ in Swedish – written across his forehead).

“I try to try to channel some sort of inner struggle,” says Murphy, reflecting on his debauched stage persona. “When we first started off with the band, everything that was going on on stage was real. I would curl up in a ball and start crying to get into this [state of] self-hatred.” He pauses. “I want to keep being this kind of decadent person on stage because it’s how a lot of people feel – and they like seeing this asshole.”

Later on that night, Murphy is a man reborn. “I destroyed my life in Barcelona,” he announces plainly to the crowd, pouring beer down his protruding, tattooed belly. He jokes that he’s the Swedish House Mafia and denounces “this fucking house shit” from the nearby Boiler Room x Cupra stage. It’s this on-stage magnetism that makes it near-impossible to peel your eyes away him. Blowing cartoon kisses to the crowd, he thrusts the air mic and screams down the mic: “But then I come out here and see all you fucking freaks – freaks never die!”

Cave World is out July 8