When you hold director David Dobkin’s “The Change-Up” next to his 2005 comedy “Wedding Crashers,” it literally boggles the mind that these two films came from the same director.

Not to say “Wedding Crashers” is a cinematic achievement of the highest order, but it’s a film that keeps the laughs coming throughout and most importantly, understands the dynamics of male friendship. “The Change-Up” is a different story entirely. It does none of these things, and when it attempts to, it fails massively — making it easily one of the worst films of the summer.

The plot is about as complex as your average restaurant menu. Single, unmotivated Mitch (Ryan Reynolds) swap lives with hard-working lawyer and dad Dave (Jason Bateman) right when they’re about to face some of the biggest professional and personal obligations of their lives. The two quickly try to recreate the circumstances of their switch, which happened to involve peeing in a fountain.

The plot is perfunctory at best. The entire narrative arc of Dave and Mitch’s quest to get their bodies switched back is them waiting around for a phone call telling them where the fountain they have to urinate in has been moved to. It’s a sad excuse for a plot and shows how little thought was put into solving the film’s main narrative conflict.

A slight plot might be forgivable if the film was funny enough to distract from its lack of narrative window dressing, but the film’s humor goes from corny to obvious to juvenile on a level that even your inner 12-year-old may think is too lowbrow.

The characters are no better. Dave and Mitch aren’t exactly likeable when the film starts, and watching them make a complete mess of each other’s lives does nothing to make you root for them.

Bateman, who can usually coax some semblance of humor out of the lamest jokes, simply cannot do a good Reynolds imitation (which mostly involves him acting like an idiot and swearing a lot in inappropriate situations), and Reynolds crashes and burns in almost every scene, disposing of what little goodwill he had left over from last year’s spectacular “Buried.”

The supporting cast fares a bit better. As Dave’s wife, Leslie Mann plays a weaker variation on the frustrated wife role she played in “Knocked Up,” and she brings a beaten-down humanity to a film sorely lacking it. Olivia Wilde is asked to be a charming, too-good-to-be-true love interest, and she does that very well, and Alan Arkin is sorely underused as Mitch’s disapproving father.

So much about “The Change-Up” just feels glossy and manufactured, made worse by the film’s odd reliance on sloppy CGI. For instance, Dave’s infant twins are rapidly flickering in and out of lackluster CGI when they need to start playing with knives or spray feces onto Jason Bateman’s face. The CGI just adds another weird, distancing element to a film that’s already overflowing with them, making the whole thing feel even more manufactured.

There is no good reason to subject yourself to “The Change-Up.” This summer has been overflowing with strong R-rated comedies, from “Bad Teacher” to “Horrible Bosses” to “Friends With Benefits,” and all of them funnier and with more heart than “The Change-Up” could ever dream of having. A cinematic black hole, the film lacks logic, humor or any sort of recognizable human behavior from its main characters; it’s a film so terrible that you will wish none of its fine collection of actors had ever succeeded, just so you wouldn’t have to be sitting in a theater watching this terrible, terrible film.