Is “Dumb and Dumber” really 20 years old? On the evidence of “Dumb and Dumber To,” Harry and Lloyd — and the giddy moron humor they embody, embrace, and expel — are eternal. There’s absolutely no need for this belated sequel, other than the fact that costar Jim Carrey and writer-directors Bobby and Peter Farrelly (a.k.a. Providence’s finest) could use the career lift. Jeff Daniels, as always, seems to be doing just fine being Jeff Daniels. But everyone has piled into this dumber, sillier, more consistently funny reprise with an enthusiasm that’s infectious, and not in a low-grade medical way.
While “Dumb and Dumber To” picks up two decades after the original, nothing much has changed, literally in the case of Lloyd (Carrey), who has been in a catatonic state the entire time. He snaps out of it, gets his hair styled in the familiar bowl cut and rejoins Harry (Daniels) — who still sports his tragic blond blowout — on a road trip to find the latter’s long-lost daughter, whom a youthful one-night stand (Kathleen Turner) gave up for adoption. Harry needs a kidney, and it takes him a while to realize his own adoptive Asian parents (Michael Yama and Nancy Yee) aren’t a genetic match.
There’s a plot of sorts, involving the grown daughter — played by Rachel Melvin as a charming ding-a-ling — attending a highbrow KEN conference while her evil stepmother (Laurie Holden) schemes with the strapping handyman (Rob Riggle) to murder her way into millions. Ho-hum. The moth-eaten pleasures of “Dumb and Dumber To” have far more to do with Carrey, Daniels, and the Farrellys competing to out-stupid each other in novel and cringingly amusing ways.
As usual, the brothers don’t toss away a single idea, and some of the misfires are vile; there’s a fantasy-flashback joke involving the daughter’s first period that I’d pay to have removed from my memory bank. But the batting average is surprisingly high, not so much in belly laughs as in steady-state giggles prompted by expert sight gags and one-liners that display the heroes’ proud idiocy. Lloyd during a boring spell on the road: “Want to play ‘He Who Smelt It, Dealt It’? It’s complicated.” Lloyd, on being told the drinks at a shindig are gratis: “Hmm. Sounds expensive.” Penny: “I’ve always wanted to go to India and work in a Leprechaun colony.” Lloyd, after a pause: “I think you mean Ireland.”
If that suggests that Carrey carries the load of the comedy, that’s only because Daniels’s Harry is so sweetly, densely reactive. True, Carrey has more to prove at this point in his career, and his high-impact energy can be grating. But then the Farrellys will park their camera as the star eats a hot dog, with mustard, in one go without hands, simply for the disgust-o enjoyment of it. You almost feel like applauding — and then taking a shower.
“Dumb and Dumber To” is shameless enough to feature a groping-granny scene and genial enough to make you forgive the visual joke that caps it; it’s a movie to make you groan and smile in equal guilty measure. The sequel finds room for return visits by Brady Bluhm as the little blind boy downstairs, now all growed up, by the Mutt Cutt car, and — if you stick around long enough — by the Farrellys’ good-luck charm, former Bruin Cam Neely. Look fast in an early scene for lonesome Bill Murray, going undercover as this movie’s very own Walter White. The principal players, including Turner, have all gotten older, but, baby, haven’t we all? To quote Lloyd, “Age is just a letter, man.”