What would it take to make you fall off the upstairs balcony at your house in the middle of the day? Could you imagine being so intoxicated by your own karaoke performance of "The Humpty Dance" that it sends you a-tumbling?

This is one of a series of ridiculously farfetched events that make up "Mother's Day," the third and worst installment in veteran director Garry Marshall's trio of starry ensemble holiday rom-coms. Even if stars Jennifer Aniston, Julia Roberts and Kate Hudson are mom's all-time favorites, don't subject her to this cloying, plotless dose of saccharine unless she's done you wrong.

The bloopers that play amid the closing credits — one in which Aniston un-hilariously calls Roberts by her real name instead of her character's — are some of the funniest moments in the film.

Like "Valentine's Day" and "New Year's Eve" before it, "Mother's Day" introduces various characters whose stories intertwine as they prepare for the title holiday. And, like its predecessors, this latest Marshall romp boasts an extensive all-star cast, including Hector Elizondo, Margo Martindale, Jason Sudeikis, Timothy Olyphant and Jennifer Garner.

We meet everyone a week before Mother's Day, as family drama reigns.

Sandy (Aniston) is dealing with the fact that her two sons might spend Mother's Day with her ex-husband, Henry (Olyphant), whose much younger new wife wants to bond with them.

Sandy's friend Jesse (Hudson) is happy with her husband and their toddler — it's her own racist mother (Martindale) who's the problem.

Kristin (Britt Robertson) is a new mom who feels she can't marry her baby's father until she resolves her own maternal issues: meeting her biological mother. In keeping with the whole farfetched thing, she decides the best way to do it is to surprise the woman during a high-profile public appearance.

Bradley (Sudeikis), the one who takes the unlikely balcony fall, is a widowed dad trying to figure out how to celebrate Mother's Day with his two teenage daughters a year after their mom's death. Sudeikis gives it his all, but his character is painfully inconsistent and outdated. He coaches the girls' soccer team and has an oracle of close female friends at the gym he runs, but is so weirded out when his 16-year-old says she needs tampons that he refuses to write the word on his shopping list. What year is this?!

Meanwhile, Roberts plays home shopping maven Miranda Collins, who's selling this Mother's Day's must-have crystal pendant. Her severe Anna Wintour bob provides a little humor, but Miranda's determined insistence that she's proud to have chosen work over parenting — and the wistful look that says it's not really true — seems trite.

British comic Jack Whitehall is the only standout. He plays Kristin's aspiring comedian boyfriend, and the scenes of him competing in a comedy club's standup contest are easily the film's best.

The clunky screenplay by Anya Kochoff Romano, Matthew Walker and Tom Hines tries to weave these characters' stories together as their crises culminate on Mother's Day. But the film's only real plot is that Mother's Day is a holiday. Its exploration of maternal relationships never dips below the surface, nor is it funny enough to justify such superficiality. Plus tying in tales of budding romance is a weird fit.

This is the most universal experience on Earth we're talking about — having a mother — yet there's no connective insight here to balance the farfetched ridiculousness of the characters' actions.

Mom really deserves better.

"Mother's Day," an Open Road Films release, is rated PG-13 by the Motion Picture Association of America for "language and some suggestive material." Running time: 118 minutes. One star out of four.

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MPAA Definition of PG-13: Parents strongly cautioned. Some material may be inappropriate for children under 13.

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Follow AP Entertainment Writer Sandy Cohen at www.twitter.com/APSandy .