Hot Tub Time Machine 2 is the Platonic ideal of a sorta-welcome comedy sequel no one really needs. It has arrived five years on, sans its biggest star (John Cusack) and, like a parched succubus, drains its source material’s surplus of goodwill to survive.

The first film gave a hearty, heartfelt shout-out to the 1980s, wedding raunch to reminiscence in a consistently funny story of do-over wish fulfillment about four guys sent back in time. Part two nearly goes hoarse screaming its reasons to exist, the most persuasive being to watch returning stars Rob Corddry, Craig Robinson and Clark Duke’s comedic chemistry and wild, woolly improv skills; Corddry and Robinson’s profane doo-wop diss of Duke’s braininess is particularly amusing.

For those who forgot (or roughly 95% of anyone who saw it), HTTM 2 recaps the original film’s ending. Having traveled back to 1986, two of the friends built billion-dollar empires on future knowledge. Id-driven imp Lou (Corddry) invented the Internet while Nick (Robinson) beat artists we know and love to the punch by preemptively writing their hit songs. (A montage of his “originals,” and the cameos that come with them, are also good for a chuckle.)

Meanwhile, Adam (who was played by Cusack) is off on “an experiential journey” and Adam’s nephew, Jacob (Duke), is still an unconfident dweeb whose dreams outweigh his daring. He’s arguably worse off under the thumb of Lou, whom we learned was his father and who treats life like a series of gauntlets. Like how few clothes he can wear in public without getting arrested; how many paintings of him screwing wild animals (or asserting “power over nature” as he puts it) he can hang; or how many people he can alienate and ruin.

Lou’s callous piggishness bites him in the ass —  or, more accurately, the genitals — as an unseen killer unloads a shotgun into Lou’s pleasure center at a party. Before Lou dies, Nick and Jacob drag him into the hot tub, intending to go back in the past to head Lou’s assassin off at the pass. However, the hot tub time machine sends people where they need to go, not where they want to go. Thus, they arrive in 2025, meaning Lou’s killer has traveled from the future “like Looper!,” Robinson squeals, excitedly name-checking one of many time-travel movie peers with wiseass glee.

Philosophically speaking, HTTM 2’s future vision feels as hopeless as Looper. As Nick says, “shit gets kind of dark” given the schadenfreude underneath this world’s beveled, shiny exterior. And the script’s future jokes feel like a bottom-shelf batch of social-satire jungle juice with a funky aftertaste. Smart cars are sentient now and have sensitive feelings. Tablets are repurposed as … uh … receptacles rather than just a visual aid for self-satisfaction. Then there’s the toxic, nanobot-infused semen that, well, you sort of have to see.

Or not. You sense director Steve Pink and writer Josh Heald don’t much care. Even at its funniest (and HTTM 2 occasionally hits riotous heights), navigating the future seems rigged solely to put giggly distance between Lou’s murder and its convoluted solution. It’s most apparent when the trio picks up another Adam (Adam Scott). This skirt-wearing, almond milk-drinking milquetoast metrosexual comes along for the ride only to find his painfully bland life upset by Lou’s debauchery. So desperate is HTTM 2 to tweak Adam’s temperance that it loses what little urgency it had.

Strangely, the film is most interesting when it tilts the trio into a coke-snorting, bottle-chugging Tin Man (Lou), Scarecrow (Jacob) and Cowardly Lion (Nick). In these moments, it recalls the somber subtext of the original, suggesting perhaps no time loop can save us from our worst impulses and twits are twits no matter the timeline. But it beats a hasty retreat to punctured scrotums and, in the film’s most lifeless bit, virtually violated anuses. (It admirably doubles down on the original’s attempt to poke a hole in homophobia but in doing so stretches the tissue too thin.)

Like Harold and Kumar Escape from Guantanamo Bay and Horrible Bosses 2 before it, Hot Tub Time Machine 2 proves some bottles aren’t big enough to hold much more than a single bolt of lightning.