“Hot Tub Time Machine” gets points for its fearlessly blunt title; too bad it oversells the fun quotient by about a mile.

By all accounts, “Hot Tub” should be a nonstop laughing spree — screenwriters Josh Heald, Sean Anders and John Morris were clearly too busy jam-packing their script with comedic brilliance to bother with the title — but most of the humor feels halfhearted. It’s more like “Tepid Bathwater Time Machine.”

Fortunately, the trio of writers understood that the setup is often the dullest part of a high concept comedy, and they breeze over the trials of tribulations of Adam (John Cusack), Nick (Craig Robinson) and Lou (Rob Corddry), three high school friends who’ve drifted apart. Somebody’s girlfriend just moved out, another one has marital problems, there’s a suicide attempt thrown in there. Yada, yada, yada. Within 15 minutes, these guys are in the tub and back in time. Joined by Adam’s nephew Jacob (Clark Duke), they had taken a trip to their old ski resort stomping grounds, only to find that their hotel hot tub was the only source of potential fun in the dilapidated village.

After a spin in the magical tub, they’re back in the ’80s, where the three adults inhabit their teenage bodies while Jacob remains his normal self. A mysterious repairman (Chevy Chase) hints that they must not change anything or they may never get back to the present.

The requisite ’80s jokes all make an appearance, from leg warmers to giant cell phones to hair metal bands. A douchey ski school instructor recites “Red Dawn” and has a hankering the weird folks from the future might be commies.

The soundtrack pumps out power ballad after power ballad to remind us that in fact, these characters are still in the past. Rather than servicing as period details though, the songs turn into the punchlines, with the script increasingly relying on musical cues to drum up laughter.

“The Safety Dance,” “(I Just) Died in Your Arms” and “Jessie’s Girl” may have been inherently funny at some point in time, but in the wake of “I Love the ’80s” and literal music videos on YouTube, I think the moment has passed.

Still, the film has a few winning gags up its sleeve — most

prominently a recurring bit with Mr. George McFly himself, Crispin Glover, as a bellman who’s destined to lose an arm.

It also doesn’t hurt that the film gives Robinson his biggest role in a film yet, and he manages to turn at least half of his tired comedic tropes into gold just by virtue of his superb timing. Duke does some good work also as the only one too concerned with getting back to the present, as his very existence depends on it.

Unfortunately, “Hot Tub Time Machine” fills in the blanks with the most expected of jokes most of the time. Its title suggests either wryness or laziness; the rest of the script seems to confirm it’s the latter.