Over the last 20+ years and some 4,000 screenings, I have tried to hold sacred perhaps THE cardinal rule of the moviegoing experience, and that of course is:

NO TALKING.

Maybe once every five or six screenings I’ll make a quiet observation to a fellow critic seated next to me, or I’ll ask a question of a colleague. But even on those occasions, I keep it quick and quiet.

“Mother’s Day” broke me down. I couldn’t help myself. On at least a half-dozen occasions, I was so dumbfounded by what was transpiring onscreen I blurted out an immediate reaction — and at least twice, I smacked the guy next to me on the shoulder. (Sorry, Bill Stamets!)

A paraphrased recap of some of the comments I muttered under my breath (or at least I hope it was under my breath and not a full-out cry for help):

• I’m pretty sure not a single character in this Atlanta-set movie speaks with a Southern accent. Tax break, anyone?

• Did that old guy Texas redneck who wears patriotic clothing and has a chicken wing literally hanging out of his mouth when he drives his oversized motor home really call his daughter’s Indian husband a towel-head shortly after meeting him? For laughs? And when the redneck’s wife sees a lesbian from behind, she calls her a “he”? What year is this?

• Gee, I really hope COORS LIGHT, THE FOUR SEASONS, FIJI BOTTLED WATER, CADILLAC, M&M’s, SKITTLES et al. are happy with the blatant product placement shots in this movie.

• The owner of a bar called Shorty’s is a little person? Really?

• You’re giving us the old “character delivers a monologue with her back turned, not realizing her intended audience has exited the room” bit? Come on!

• By all means, after an adult Caucasian is injured while performing a karaoke version of “The Humpty Dance,” cut to the sassy black woman saying, “That’s what happens when white people try to rap,” and top it off with a shot of a black child dancing with impeccable rhythm.

This movie never should have seen the light of day or the dark of theater.

“Mother’s Day” is Garry Marshall’s third star-studded, mawkish, bloated, holiday-themed film with intertwining characters and story lines. First there was the mediocre “Valentine’s Day” (2010). Then we were subjected to the sappy but relatively harmless “New Year’s Eve” (2011).

But nothing could have prepared us for the offensively stupid, shamelessly manipulative, ridiculously predictable and hopelessly dated crapfest that is “Mother’s Day.”

Nearly everyone in the talented and likable cast, including a number of Garry Marshall regulars, is to be commended for trying to lend some air of authenticity to the broadly sketched characters — even if nobody succeeds.

Jennifer Aniston plays Sandy, a divorced mom of two boys who has hopes of getting back together with her rakishly handsome ex Henry (Timothy Olyphant) — until Henry tells Sandy he recently got married to the twentysomething bombshell Tina (Shay Mitchell).

Kate Hudson’s Jesse is married to a doctor named Russell (Aasif Mandvi), and they have a toddler son, but she hasn’t told her parents Earl and Flo (Robert Pine and Margo Martindale) because they’re horrible racists who wouldn’t approve. Oh, and she’s been lying to Russell all this time, telling him her parents are in ill health and living in a retirement facility.

Sarah Chalke plays Jesse’s lesbian sister, who hasn’t told her parents (you remember the lovable Earl and Flo) about HER marriage because they’re just as homophobic as they are racist. Hilarious!

Jason Sudeikis is a widower and father of two daughters who is still clinging to the memory of his wife, a military hero (played by Jennifer Garner in the obligatory sad late-night video sequence.) And you better believe we get an over-the-top remembering-mom scene complete with an orchestral version of “Taps.”

Julia Roberts plays Miranda, a career-driven TV hostess who peddles hideous jewelry and a self-help book.

Britt Robertson is Kristin, a young mother who can’t fully commit to the father, an aspiring stand-up comedian. As Kristin explains to Jesse, she was adopted and she has always wondered about her birth mother. “I have abandonment issues,” says Kristin.

Thanks Kristin. We got that when you told us about being adopted and never hearing from your birth mother.

From just about everything we’ve read and heard about Garry Marshall over the years, he’s a kind and nurturing fellow who always finds roles in his films for regulars such as Hector Elizondo, Larry Miller and Sandra Taylor. (He also often finds room for himself, his family members — and relatives of cast members.)

That’s nice.

Marshall apparently also gets a kick out of Julia Roberts referencing “Pretty Woman.” In a closing credits scene in “Valentine’s Day,” a limo driver points out Rodeo Drive to Roberts’ character, and asks if she ever shopped there.

“I did once,” she replies. “It was a big mistake. Big. Huge.”

This of course is a play on one of Vivian’s most famous lines in “Pretty Woman,” when she gains her revenge on the snooty Rodeo Drive shop assistant who had turned away her business the day before.

In “Pretty Woman,” Elizondo played a hotel executive who takes a fatherly liking to “Miss Vivian” and teaches her about the proper use of silverware.

“I definitely have the salad fork,” says Vivian. “The rest of the silverware is a little confusing.”

In “Mother’s Day,” Roberts’ Miranda is having lunch when her manager Lance, played by Elizondo, interrupts to dispense some pearls of wisdom. Apropos of nothing, Lance tells Miranda, “You definitely have the salad fork.”

In what appears to be yet another distracting and annoying ‘wink-wink’ touch, Roberts’ Miranda sports a terrible and unflattering wig. According to People, it’s literally the same wig worn by Roberts in “Helix,” the movie within a movie in “Notting Hill.”

From Hitchcock to Spielberg to those rascals at Pixar, filmmakers have often dropped inside references to their own previous films, or movies they loved.

Usually there’s at least a touch of subtlety. Like just about everything else in “Mother’s Day,” the nod to the earlier movies are clumsy and pointless and obvious.

Zero stars

Open Road presents a film directed by Garry Marshall and written by Anya Kochoff Romano, Matt Walker and Tom Hines. Running time: 118 minutes. Rated PG-13 (for language and some suggestive material). Opens Friday at local theaters.