Beware the grandma. Nearly as ubiquitous as a head-cocking canine in bad romantic comedies, the clueless-elder cameo is almost always a sure sign that the filmmakers either a) ran out of ideas or b) didn’t have any good ones in the first place.

Throw—with great force—Made of Honor into the latter category. And worry about Patrick Dempsey, who has used his mid-career makeover on Grey’s Anatomy to star in exactly one winning film (last year’s Enchanted) before boomeranging back to Can’t Buy Me Love territory, apparently forgetting that while such late-’80s swill launched his career, it also threatened to box him into formulaic roles forever.

Dempsey literally grows young again in Made of Honor’s opening scene, his face creepily covered in what looks like flesh-colored fondant as his character, Tom, is shown partying in college and meeting cute his future best friend, Hannah (Michelle Monaghan). Ten years later, the two have no romantic relationship yet a standing Sunday date in which they go out to dinner, play guess-which-dessert-I’m-getting, and generally giggle and act adorable together. Their conversation consists of one topic: Tom may be a cad whose personal version of The Rules prevents his gaggle of girlfriends from getting too close, but at least he’s honest with them. (This guy is so friggin’ honest, in fact, he or another character will mention the trait approximately a dozen more times.)

You’ll be ready to retch even before the story, written by a trio of scripters, reaches Act 2. Hannah travels to Scotland for a six-week business trip (she’s an art restorer) and after a series of missed phone calls, soul-bearing basketball games with the guys (Tom, who invented the coffee collar, is comfortably unemployed), and a frowny-faced solo dessert outing (the lovelorn wretch is forced to order two pieces of cake because Hannah’s not there to offer him a bite of hers), Tom decides that she’s the One. And he’s just bursting to tell her when they meet for a welcome-back dinner. Except Hannah has made it a party of three, introducing Tom to Colin (Kevin McKidd), her perfect Scottish fiancé. Cue Tom crashing into a waiter. Twice.

Unfathomably, Made of Honor gets worse from there. This isn’t a he-said-she-said comedy, yet the dialogue can be summarized thusly: Hannah’s female friends go, “Awww!” “Eeeeee!” and “Oooooh!” whenever any topic from Colin to the weather is mentioned. (Except for Hannah’s grandma, who just grins idiotically as she wears a sex toy as a necklace.) And Tom’s friends say things such as, “Any time is the right time to say I love you!” They also quiz him on maid-of-honor duties. Oh, did I forget to mention this crucial and most absurd plot point? Hannah wants Tom to be her best gal. Which in itself is fine, except no one will refer to him as anything but “maid” of honor, seemingly for no other reason than it’s allegedly funny. Tom’s friends encourage him to accept the responsibility and prep him like drill sergeants, the better for Tom to sabotage the wedding under the radar.

Among the movie’s many other sins is Weiland’s occasionally awful camera work, including blurred shots through a revolving door and a nauseating dinner-table spin when Hannah’s telling Tom the news. (Though maybe we shouldn’t expect much from the director of City Slickers II: The Legend of Curly’s Gold.) There’s a cruel undercurrent of an ugly-people-are-funny mentality that will make some viewers flash back to high school: On several occasions, Tom and his other good-looking friends stare incredulously at a “nerd” who likes to play ball with them at the gym, and Hannah’s friends, none model-perfect yet far from unattractive, are first shot as a trio with music that suggests the freaks have arrived.

Dempsey can’t do anything to save the paper-thin Tom, and the minor characters are so generic the actors aren’t worth mentioning (except for Sydney Pollack, embarrassing as Tom’s father, a compulsive marrier who negotiates sex in his prenups). Monaghan comes close to emerging with her dignity semi-intact. But Hannah is dumb as a bouquet of rocks when it comes to her newfound love, and unbelievable in her knee-jerk reactions to Tom the very few times he screws something up. Nobody survives Made of Honor unscathed.