Before Billy Madison and Happy Gilmore, and before his bit parts in early 90s comedies, Adam Sandler introduced himself to the film world with Going Overboard, an all-but-forgotten 1989 comedy that presents him in the guise of cruise ship attendant Shecky Moscovitz. Shecky fancies himself a comedian, but can’t stand the ship’s actual comedian, Dickie Diamond, played by Scott LaRose, whose stand-up routine appeals equally to the two main demographics on board – wealthy retirees, and the Miss America contestants who have decided to take the high seas before they port in Cancun for their annual beauty competition.

I thought I knew what lowest common denominator was before I saw Going Overboard, but it blew my preonceptions out of the water, since this is genuinely one of the worst films I’ve ever seen – so bad it makes every other Sandler film seem like an arthouse masterpiece. This much be unwatchable for even the most die-hard Sandler fans, perhaps explaining why it’s beeen tacitly consigned to oblivion, despite receiving a brief revival in the wake of Billy Madison and Happy Gilmore. Apparently it really was shot on a six-day cruise from New Orleans to Cancun, with real Miss America contestants on board, but the ocean liner still feels like a non-backdrop here, a lazy way to avoid anything resembling atmosphere, place or pace.

Dire as it is, though, Going Overboard is still a fascinating peek into the genesis of Sandler’s comic reign – and it’s probably safe to say that you can’t fully grasp the Happy Madison brand without seeing where it all originated here, since the entire film is driven by Sandler’s sneaking suspicion that he’s not funny, or at least not funny in a conventional way. The wittiest comedy usually has some continuity with stand-up – an observational component that can stand alone – but Sandler’s comedy has never worked that way. In that sense, he’s the polar opposite of Jerry Seinfeld, the other pre-eminent Jewish comedian of the 1990s. in Seinfeld, every plot feels extrapolated from Jerry’s opening monologue, and vice versa – the two are totally symbiotic – while Jerry often breaks into observational routines amongst his friends, and frequently tries out new comic bits with them before taking his show on the road.

Whereas Seinfeld plays a stand-up comedian in his fictional version of himself, Sandler pits himself against a stand-up – Dickie Diamond, who was apparently modelled roughtly on Andrew Dice Clay. Admittedly, at times, Sandler does try to style himself as a stand-up here, especially in his half-hearted “meta” addresses to camera, often paired with cringeworthy chest flexes, the first and last time in his career that he’d have a decent enough rig to show off. But these gestures are all pretty impotent, and most of the film is driven by Sandler’s anarchic, idiotic, propulsive line of flight from the wit of stand-up – his desperation to carve out a comic niche for himself at all cost. In effect, he tries every comic option at his disposal, throwing everything at the wall but finding almost nothing sticking, at least not permanently.

This gives Going Overboard a crazy No Wave vibe, right down to the wrong lenses (the cinematographer forgot to bring the correct ones) and the poor sound design, which makes it all seem dubbed. There’s very little plot and not much in the way of real set pieces – just an unmediated expression of Sandler’s unconscious. At times it’s closer to a beach film, a variety show or (at a stretch) a National Lampoon pastiche than a regular movie, but for the most part it’s more like anti-cinema, an inadvertent or idiotic Dadism that could work quite well as an interlude in some of David Lynch or Harmonie Korine’s weirder films, but falls totally flat as a fratboy comedy. If it were just like watching amateur Theatresports that would be bad enough, but this is like Theatresports where everyone is saying no, where everyone is rejecting the offer, meaning that there’s nothing outside of Sandler’s own insane self-regard.

Despite all that anarchic energy – or perhaps just because of it – Sandler isn’t funny at all yet. In fact, you really see how unlikely it was that he would become funny, foreshadowing how fleeting his stretch of decent films – from Billy Madison through to Big Daddy – would turn out to be. In part, that’s because Sandler hasn’t accepted that his best comic bet is to be totally abject and infantile – he hasn’t yet embraced the victimology that would endure through his career from Billy Madison on. Put more bluntly, he needs a bully to come into his own comically, so it’s no surprise that the best scene – perhaps the only good scene – here sees him pitted against an aggressive heckler, played by Billy Bob Thornton in a brief cameo.

While Shecky does finally get to the stand-up mike, his material is awful – and his material isn’t the point anyway. Instead, he uses the mike to yell over the crowd and drown his own insecurities out of existence, collapsing stand-up in upon itself in ways that also anticipate the involuted style of his later anti-stand-up. Yet even that gesture can’t provide Going Overboard with a single genuinely comic moment in its long running-time – and at 107 minutes this is bizarrely and interminably feature-length, despite overstaying its welcome in the first five minutes. You can only assume the editors had to make an executive decision not to remove any of the bad stuff, since that would have meant removing the entire film, whose sheer scale is perhaps the most incredible aspect of one of the worst mainstream comedies ever created.