It's difficult to say how many times the whole "switching bodies" plot has been used in Hollywood over the years. At the moment, Freaky Friday (all fifty versions of it), All Of Me, Wish Upon A Star (that Disney romp that Katherine Heigl wishes she could forget), The Hot Chick, Prelude to a Kiss, and Dream a Little Dream are the only ones coming to mind. But that's still a hefty number of similar plots, and I know there are a fuck ton of others I probably can't think of. In any case, considering how overused the storyline is, David Dobkin's (of Wedding Crashers fame) The Change-Up does its best to bring some freshness to a stale idea.
With the oh so clever tagline, "Who says men can't change?", The Hangover writers Jon Lucas (who also wrote the shitastic Four Christmases and Ghosts of Girlfriends Past) and Scott Moore (who shares the same co-writing resume) present the possibility that once you have literally walked a mile in someone else's shoes, it is possible to see life differently and maybe even metamorphose into a better person. For Mitch Planko (Ryan Reynolds), this unwilling transformation is what audiences would like to believe is necessary.
Relegated to the role of slacker content with getting high and "keeping company with a number of nice ladies," Mitch is clearly, from a conventional standpoint, the one to benefit most from being forced into his best friend Dave's (Jason Bateman) body. After all, Dave is a family man with a stable job, whereas Mitch's life is a hollow existence of eking out a living as an actor in tampon commercials and lornos (light pornos). Though, as it turns out, Mitch isn't shy about expressing how much he absolutely loathes having anyone depend on him for things, least of all three children and a nagging wife (Leslie Mann).
Dave, on the other hand, is eager to experience the benefits of singledom and independence--something he missed out on in his twenties. However, once he gets the opportunity to have sex with the object of his desire, Sabrina (Olivia Wilde), he discovers he doesn't really want to (which we all know is a goddamn lie, but for the sake of a character arc, I suppose he had to feign disinterest).
After finding out where the fountain they pissed in was moved to (a lovely beacon of commerce called Peachtree Galleria--places in Atlanta are fond of incorporating the word "peachtree"), the two now intimately acquainted friends rush to it so they can reverse the spell the fountain cast on them. As shoppers gawk at them urinating freely, Dave and Mitch exchange one final heart to heart about the changes they've been forced to undergo as a result of being stuck in each other's bodies.
Of course, it wouldn't be a Jon Lucas/Scott Moore script if the movie was all-out cheesy and bromantic. Which is why the concluding line of The Change-Up consists of Dave noting, "Is it weird that I miss your penis?" and Mitch, without missing a beat, responding, "It'd be weird if you didn't."