Dumb and Dumber To Jim Carrey, Jeff Daniels, Rob Riggle. Directed by Peter and Bobby Farrelly. Rated PG-13. Opens Friday.

It took 20 years for the creators of Dumb and Dumber to get back together for a sequel (the 2003 prequel Dumb and Dumberer: When Harry Met Lloyd didn’t involve any of the original creative team), and the years have not exactly been kind to the movie’s brand of ultra-lowbrow humor. The first Dumb and Dumber has built up quite a cult following, and directors Peter and Bobby Farrelly do their best to recapture its appeal in Dumb and Dumber To, but the effort comes across as desperate and sad, with meager laughs and sloppy storytelling.

Stars Jim Carrey and Jeff Daniels return as dim-witted friends Lloyd and Harry, respectively, and the manic energy they brought to the parts 20 years ago has diminished a bit, although they’re still game for whatever ridiculous, disgusting scenario the Farrellys want to throw them into. As in the first movie, the pair set out on a road trip, this time in search of the daughter that Harry never knew he had. The setup is even thinner than it was the first time around, with the villains of the piece (led by Rob Riggle as a con man and his military-operative twin brother) not showing up until a good half-hour into the poorly paced movie. The finale, set at a TED-like academic conference, is interminable, dragging out every meager reveal like it’s a twist in a sophisticated thriller.

Of course, despite the presence of six credited writers (including the Farrellys), the plot is not really the point, and the movie throws out as many jokes as possible in the hopes that some of them will land. Almost none of them do, and the gross-out humor that grabbed audiences in the first movie is even more unpleasant and forced this time around. Even worse is the mean-spirited running joke around Kathleen Turner as Fraida Felcher, the mother of Harry’s long-lost child, which consists entirely of insults about Turner’s current appearance. Instead of coming off as lovable doofuses, Lloyd and Harry often act like bullies, which undercuts what little appeal they had in the first place.

Carrey and Daniels, both now in their 50s, may look a little like they’re trying to remind a younger generation that they were cool once, but they give exuberant performances of every humiliating set piece and poorly written line. The production, though, isn’t nearly as professional, with a flat, cheap-looking visual style that’s barely sitcom-level. Nostalgic fans who’ve watched the original movie dozens of times on TV may get a kick out of the periodic callbacks, but even they will probably end up disappointed at having waited two decades for such a slapdash follow-up to an overrated sentimental favorite.