Anyone who requires proof that Ryan Reynolds can be funny—and after his starring roles in bombs such as Waiting... and Van Wilder, quite a few probably do—need only give the guy four minutes. That’s the time it takes for Reynolds, swaddled in his Just Friends fat suit, to mouth the words to All-4-One’s luv ballad “I Swear,” complete with goofy hand gestures, exaggerated expressions, and a ridiculous attempt to sing the song’s multiple vocals all at once.

The bad news: This performance plays during the end credits of director Roger Kumble’s by-the-book contribution to holiday-themed romantic comedies. The good news: Just Friends is not quite as stupid as it looks—though Kumble (The Sweetest Thing) at times renders its comedy with a broadness that makes The Ice Harvest look like Masterpiece Theatre—so most moviegoers should be pleasantly diverted until Reynolds’ encore.

The setup is relatively simple. Chris (Reynolds), once a plus-size high-school reject, has slimmed down and become a successful Los Angeles music producer. While jetting with his girlfriend/client, the talentless, Courtney Love Jr. pop star Samantha James (a brash but funny Anna Faris), to France, Chris is forced by an aircraft malfunction to land in his New Jersey hometown, which he hasn’t been back to in 10 years.

So he surprises his mom (a too-flaky Julie Haggarty) and visits the old watering hole, where he spots Jamie (Amy Smart), the woman he was best buds with in high school—and, of course, the girl he secretly loved and was eventually rejected by. When a drunk friend suggests he could probably win her over now, Chris postpones his Paris trip and distracts Samantha in an attempt to do just that.

Here’s where things get a little mixed up. Scriptwriter Adam Davis—whose only previous big-screen credit is a 2001 MTV-backed movie called Spring Break Lawyer (!)—can’t seem to decide whether Chris is going after Jamie for love or revenge. One minute he’s looking longingly at his Jamie-is-the-best scribblings from high school; the next he’s boasting to a friend that a rented Porsche and callous attitude will make Jamie fall for him, because she was notorious for dating only jerks.

OK, so it’s a ploy, but one that’s not very well-executed: Chris never really acts like an ass during their handful of dates—an old diner waitress pinching your cheeks and saying in a baby voice that you’re “not a chubby bunny anymore!” would make anyone subtly threaten her with a fork— but the apparently highly sensitive Jamie reacts as if he were. So they take multiple trips through the infuriating love-you/hate-you cycle, with a fellow classmate, the seemingly perfect Dusty Dinkleman (Chris Klein), showing up to complicate things. None of it is very believable.

Where Davis excels is providing just the right dialogue for Reynolds’ proclivity for sometimes mannered, more often fuming sarcasm—think of him as the poor man’s Ben Stiller. Davis’ script isn’t quite worthy of Stiller himself, but it’s close, particularly with a running gag in which Chris’ younger brother, Mike (Chris Marquette), and friend Clark (Fred Ewanuick) rag on weepfest The Notebook (one of Chris’ date destinations) and its inherent “gay”-ness. The siblings’ perpetual, slap-happy feuding is just the right amount of physical comedy for anyone embarrassed to have bought a ticket to enjoy.

Unfortunately, the filmmakers elsewhere take bodily harm to brutal Home Alone levels. (The way Chris manhandles Samantha is borderline abusive.) They also give us the absurd destruction of a home that mimics a similar (and equally ineffectual) scene in Meet the Parents. It all leads to a predictable, eye-rolling end—but then “I Swear” woos you back, at least for a few minutes, in a way that All-4-One surely never intended.