We’ve all met the party guest who stumbles uninvited into a social discussion after too many rum and Cokes, one who belches that he has gay friends ad nauseum as if to prove a lack of prejudice.

Being mired in that conversation for 115 minutes is approximate to seeing I Now Pronounce You Chuck and Larry. This abysmally unfunny dud stars Adam Sandler as Chuck and Kevin James as Larry, two firemen feigning homosexuality to reap domestic partner benefits for Larry’s kids.

The bigotry shown here isn’t so much anti-gay as it is anti-humor. No groaningly obvious double entendre, homophobic spit-take or gay pun is left behind, down to a mailman used to “handling large packages through the back door with care.” Even its gay panic is played safe, right down to a will-they-or-won’t-they guy-on-guy smooch in a courtroom conclusion.

No great Sandler comedy ever has ended in the halls of justice, and Chuck and Larry is predictably bogged down with flat platitudes during a long second hour when Things Get Serious.

The film also lacks Sandler’s usual hallmarks of riotously surreal, random humor, even as it rounds up his usual suspects (Steve Buscemi, Dan Aykroyd, Rob Schneider) for cameos. (Only because of Rob Schneider’s vague Polynesian ancestry does his stereotypical Asian minister role not rankle as badly as Eddie Murphy’s similar role in Norbit.)

It would’ve been familiar, but perhaps funnier, for this sexual-orientation tale to strike farcical tones. Instead, it goes for the sound of farts, with a 500-pound man cracking off after falling with his crotch embedded in Chuck’s face. New depths are plumbed in getting worse from there.

Despite a co-writing credit, it’s hard to believe Alexander Payne and Jim Taylor had much to do with this movie. Perhaps they were forced to write not one, but two, slow-motion soap-dropping gags under a threat to obliterate their entire family line. More likely, whatever wit the duo behind Election and Sideways put in suffered rewrite rubouts from unnamed Sandler cronies.

Regardless, their names still are 50 feet tall, which original director David Dobkin (Wedding Crashers) avoided when he bailed on the project. In a scramble, Sandler tapped past collaborator Dennis Dugan. Since directing Sandler’s great Happy Gilmore and amusing Big Daddy, Dugan has aimed at filling Satan’s Multiplex with Saving Silverman, National Security and now this.

Dugan is a director for whom even the lamest Fox sitcom is too sophisticated. The peppy music accompanying fire calls is like if Carl Winslow heard jazzy saxophones en route to a hostage negotiation. Dugan’s split screens, skewed angles and shaky camera shots seem like devices from the opening credits of My Two Dads. At least that ’80s show with a semi-similar idea had laughs.

Its sole plus is James’ sweetly exasperated performance as a parent. Meanwhile, Sandler hobbles around with a cane and cigar in a strained effort to be Walter Matthau to James’ Jack Lemmon.

Problem is, there’s nothing remotely likable about Chuck; in fact, he is easily Sandler’s least likable character ever. Apart from his misogyny, Chuck meanly goads Larry about his son’s effeminate tendencies and mimics the voice of his dead wife. It’s a slap in the face to James that the film’s hetero-romance subplot — involving Jessica Biel’s hottie defense attorney — is given to Sandler.

If one of Chuck and Larry’s big messages is that there’s nothing worse than pretending to be something you’re not, here’s a call-out in that spirit to something dubiously dubbed as a comedy.