Calling it ghastly would be an act of kindness toward this woefully unfunny take-off on the cliches of Hollywood romantic comedies, the latest in the long line of broad, inane farces mocking genre movies that sprang from “Airplane” but have grown limper and lamer as the generations passed. “Date Movie” is the spawn of the “Scary Movie” franchise (the two writers, one of whom also directed, were part of the team that cobbled together the first “Scary Movie,” and had previously penned another labored spoof, the 1996 “Spy Hard”). At a mere seventy minutes, it seems interminable.

Basically the picture is just a series of sketches poking fun at scenes from popular movies, from “Pretty Woman” and “What Women Want” to “My Big Fat Greek Wedding” and “My Best Friend’s Wedding” (though there are plenty of others–far too many to catalogue here), but the most consistent targets are “Meet the Parents,” “Meet the Fockers,” “Bridget Jones’s Diary,” “The Wedding Planner” and “Hitch,”which provide the thin reed on which a semblance of plot is strung. That has to do with an overweight, lonely girl named Julia Jones (Alyson Hannigan, at first in the fat suit that seems obligatory nowadays), who slims down under a regimen ordered by her date counselor Hitch (Tony Cox), an energetic midget, in order to catch the man of her dreams. He’s Grant Funkyerdoder (Adam Campbell), who does in fact fall for her. This leads to a repetition of the “Parents” dinner-table scene with Eddie Griffin and Meera Simhan as Julia’s unlikely “Greek Wedding” dad and mom, and then to more extended “Fockers” stuff with Fred Willard and Jennifer Coolidge doing bad imitations of Dustin Hoffman and Barbra Streisand, punctuated by bits of business involving a wedding consultant named Jell-O (Valery Ortiz, with a huge, padded derriere), and Grant’s svelte, jealous erstwhile girlfriend Andy (Sophie Monk), who wants to steal him back. The movie shows it’s up-to-date by adding closing nods to “Wedding Crashers” and “King Kong” to sum things up.

As “Airplane” showed, there’s nothing inherently wrong with this sort of scattershot approach, but it’s not enough to show the audience you’ve seen the same movies they have; for a successful parody, you have to do something clever with the material you toss into the mix. As “Date Movie” rolls on, you’ll recognize the references–“Oh, there’s ‘Napoleon Dynamite,’ and ‘Say Anything’ and ‘Sleepless in Seattle’”–but that’s about all. The only things its makers add to them are loudness, grossness and sloppiness. You’re supposed to groan at some parts of this kind of melange, but that’s about the only reaction this movie ever generates. Laughter is in very short supply. (Can you really be expected to endure yet another tired jab at Michael Jackson?)

You have to sympathize with the actors trapped in the mess, trying desperately to be likable and funny under such abysmal circumstances: Hannigan’s sense of desperation is almost palpable, especially when she has to do klutzy dance moves in that fat suit (and later after she’s slimmed down). But the people you’re most likely to feel for–aside from yourself, of course–are the veterans like Willard and Coolidge, who are called upon to demean themselves with the stalest of material. Technically the picture looks as cheap and brassy as the writing is.

“Date Movie” has been directed by Aaron Seltzer with a sledgehammer, as though overemphasis could turn the dross he and Jason Friedberg have written into gold. The result is hard on the actors, but harder on us. One of the tactics he and editor Paul Hirsch most frequently resort to is an embarrassed reaction shot of one of the characters, usually shrugging and smiling. They could have gotten the same effect by simply panning the camera across the faces in the audience–minus the smiles, of course. But if you pay to see a movie like this, you do have to be ready to shrug it off.