If the devolution of bromance over the last couple of years has taught us anything, it’s that there’s nothing especially humane about the bro code, just as there’s nothing especially humane about the male bonding that it tends to involve. While that has certainly produced post-bromances along the lines of Funny People and Bad Neighbors 2: Sorority Rising, it has also left open the possibility of a post-human bromance, a possibility that is beautifully encapsulated by Daniel Kwan and Daniel Scheinert’s debut feature Swiss Army Man. Known in the industry simply as Daniels, Kwan and Scheinert have previously worked in music video, most notably on DJ Snake and Lil Jon’s “Turn Down For What,” and in many ways Swiss Army Man plays as a music video transformed into a feature length film, not merely because music pervades nearly every scene but because it is founded on exactly the kind of bizarre premise that characterises the best music videos: in this case, a flatulent corpse (Daniel Radcliffe) who manages to guide a castaway (Paul Dano) to safety, turning into his best friend in the process.

It’s the perfect blend of insanity and inanity for an instant cult classic, as Hank (Dano) rides the corpse, who he christens Manny, across the waves, until they arrive at another shore and attempt to make their way to safety. At first, it is hard to tell how much of the role of Manny is played by Radcliffe and how much is played by a prosthetic corpse, especially because the body becomes progressively dishevelled and disfigured as the journey to safety proceeds, bearing the marks of the rugged landscape as it tumbles down rocky slopes and is gnawed at by rodents, as well as undergoing its own bizarre processes of physical decay in the process. One of the pleasures of this early part of the film is the complete improbability and implausibility of it ever being feasible for even a short film, let alone a feature film. Part of what I find so appealing about music video is the way in which it take premises that would be too outlandish for mainstream cinema – a series of failed pitches – and manages to imbue them with a greater viral visibility than even the most successful blockbusters could hope to achieve. For the first twenty minutes of Swiss Army Man, that particular pleasure dovetails with the pleasure of seeing two music video directors actually having a chance to make good on their premise, while knowing all along that even if the film flops this opening sequence is guaranteed to garner more buzz and attachment than a much safer feature could ever hope to achieve.

It’s incredible, then, that a series of twists manage to expand this out into one of the most original and beautiful feature-length experiences I have had in a long time. Originality is such a common critical plaudit these days that it’s hard to know how to describe a film whose very survival as a film feels improbable at virtually ever turn, to the point where it is the film itself – and film as a medium – that feels like the real subject matter of the survival narrative that drives the action. Nevertheless, I can only describe these various turns as original in the most profound and surprising way, the most momentous of which sees Manny gradually coming to life and turning into a kind of imaginary friend and saviour figure for Hank. In another kind of film, this might be presented as a more or less straightforward hallucination – or at least establish a fairly conventional dichotomy between reality and hallucination, as well as a relatively conventional twist – but any sense that Manny is a mere projection is offset by the particular way in which he comes to life. Far from offering himself as a personality or as a receptacle for Hank’s thoughts, his body comes to life before his mind, as a series of orifices, liquids and gross-out bodily processes that Hank initially reads as part of the decomposition process, and only gradually comes to read as friendship. As he gets to know Manny’s body processes more and more, he also reads them as harbingers of their eventual rescue, making for a kind of weird survival film in which one party has already done the other the favour of making his corpse available for every convenience.

As virtually every review of the film has mentioned, it’s Manny’s anus – and Manny’s flatulence – that forms the first point of contact between the two friends, as Daniels take the fart joke to ever more hallucinatory levels of auteurist flamboyance and Manny’s anus becomes as expressive and individual as his voice, even when he learns to speak in a fairly sustained and nuanced manner. In the early stage of their relationship, a great deal of Hank’s bonding with Manny takes place through music – not only does he sing him songs and sing songs “with” him but as their friendship subsumes any need for survival it gradually takes on the quality of an extended music video, with instrumentation and melodies segueing in and out of the diegesis as seamlessly as Hank’s relationship with Manny segues in and out of the naturalistic environments within which it develops. Given that Manny’s anus is presented as an accomplished wind instrument in its own right, and the bass note to most of the musical numbers, it feels as if this ever-expanding anal communication is in some sense the quilting point at which the film’s convergence of conventional cinema and music video occurs as well, as if all the abrasive, antisocial and anal tendencies of music video as a genre were accommodated to cinema by way of a broader melodic milieu that frequently feels like an argument for musical theatre as a twenty-first century, digital medium as well.

In that sense, Manny – as he is so appropriately named – comes off as something like the perfect post-human bro. While the flatulence is front and centre, all his other gross-out bodily functions assist Hank in some way as well, from his perpetual vomiting, which provides water, to his rigor mortified erection, which acts as a compass whenever they find themselves lost in the forest. In bromances, bros are always trying to become more bro-like and less human, but here we start with something like a perfectly realised bro – a series of orifices and bodily liquids – who has to be progressively humanised, a post-human who has simply distilled the most abject parts of being human rather than exceeding or transcending them. The thing is, the perfect bro is also in some sense a substitute for women entirely, which makes them a lover or a masturbatory aid, depending on how you look at it. In many ways, the latest iteration of the bromance – or the rebranding of the buddy and male bonding films as bromance – spoke to a millennial world in which it was impossible to ignore that ultimate masturbatory function of the bro, as well as a world in which it would again be possible to approach brohood, boyhood and male bonding with the same kind of innocence – or the same lack of suspicion – ever agin.

In Swiss Army Man, that aspect of the bro is front and centre, with Manny increasingly coming to the play the role of lover – specifically, substitute for an unrequited love – and masturbatory surrogate for Hank. While the former produces some fantastic sequences, the latter is what really sustains the film, as Hank quickly moves front teaching Manny to masturbate to realising that he can actually use him to masturbate in the most expansive and all-encompassing way, leading to a series of insanely hilarious montage sequences in which he uses him as a flame-thrower, a launching-pad, a scoping device and pretty much every other object that a bro might want to have in their arsenal. At the same time, the anus is foregrounded more and more as the communicative channel between the two bros, until it feels as if it literally all that they talk about is flatulence, defecation and anal experience more generally.

Undoubtedly, that gives the film a tipsy, oneiric, masturbatory quality in itself – in the very best way, it is like watching someone masturbate for ninety minutes; or, rather, like seeing someone prepare everything they need to masturbate for ninety minutes, which is part of what gives it such an out-of-body, insane inner monologue kind of feeling at its most enjoyable moments. At the same time, however, by embracing the bro at his logical endpoint, the film ends up paradoxically reinvesting boyhood with a remediated innocence, since what makes Swiss Army Man so powerful is that this anal obsession is not presented in a knowing or sleazy light but as the manifestation of total love, the kind of love that presumably led Kwan and Scheinert to fuse themselves into Daniels over the course of their own professional bromance. For all that the film initially feels directed at an adult audience, it quickly comes to resemble The Lost Boys, Stand By Me and other boyhood classics, in a kind of corrective to Richard Linklater’s Boyhood that does away with fatherhood, and the pathos of fatherhood, altogether, or at least subsumes it along with everything else into the masturbatory proximity of Hank and Manny. It’s this unabashed love that boys have for each other that prompts some of the most visually extravagant moments in the film, as the “wilderness” gradually shrinks to a kind of giant backyard – it turns out to only be the narrowest of margins between the coast and suburbia – and Hank and Manny arrive at the threshold of civilisation only to realise that they just want to stay in the woods and play with each other forever.

For another film, that might settle quite easily and comfortably into a New Sincerity conclusion, but to its credit Swiss Army Man only becomes more anal and scatological as the sincerity rises, with Manny questioning “if my best friend keeps his farts from me, what else is he hiding and why does that make me so alone?” only for Manny to reassure him that, whatever happens, “one day some of your shit is going to meet up with some of my shit.” By the end, every emotional exchanges is contoured through their bodily fluids, processes and orifices – all of which come back to the anus – making for a conclusion that was so uncanny and weird in its anal sentimentality that I could hardly believe my eyes, as all of Hank’s friends and family gaze on at his final farewell to Manny, repelled and compelled at once. If the film as a whole recaptures the innocence of childhood in the strangest of ways, then this final sequence recaptures the strangeness of adulthood in what turns out to have been the most innocent of ways, making for one of the greatest films about growing up that I have ever seen, as well as one of the most genuinely original outings of the twenty-first century, in both mainstream cinema and music video.