Emma Street marvels at the sanity of the characters in bodyswap comedies.

Hollywood loves a body swap. Whether it’s an older person swapping bodies with a younger one (Freaky Friday, 18 Again) or a man swapping bodies with a woman (It’s A Boy Girl Thing, The Hot Chick) or a person becoming a different version of themselves (Big, 13 Going On 30). Well, in The Change-Up, a thirty-something man wakes up in the body of a thirty-something man! A different one, obviously. It would just be normal life, otherwise.

Jason Bateman and Ryan Reynolds are lifelong friends. Bateman is a successful lawyer with an impossibly hot wife, three adorable children, tons of money and a very busy schedule. Reynolds is an unsuccessful actor with a sword fixation and a lot of free time. On a drunken night out together, they tell one another – insincerely – that they wish they had the other one’s life. Unfortunately they do so whilst pissing into a magic fountain of plot contrivance. Next morning sees the inevitable:  hangovers, regrets and waking up in someone else’s body.

In order to understand why it might be desirable to be living the life of out-of-work actor who gets stoned before 10 o’clock in the morning and picks up women in antenatal classes, you have to accept the film’s basic premise that Ryan Reynolds is way hotter than Jason Bateman. I grant you that Bateman look like the pissed-off nephew of a cartoon Alan Titchmarsh for the majority of the film. Ryan Reynolds, though, appears to be morphing into Will Ferrell and the only time Will Ferrell has ever been attractive was as a giant headed blue alien in Megamind.

In body swap films generally, the mechanics behind the swap is never really explained, although curiously, while the original swap doesn’t kick in until the next morning, the return to original bodies is usually instantaneous. There’s never any explanation for this either, but then there’s no explanation for the whole phenomenon: save for a passing to nod to a spooky fairground attraction, magic earring or mischievous old Chinese lady. A quick change back generally suits the plot better. (Tom Hanks leaving Elizabeth Perkins’ car while still looking like Tom Hanks at the end of Big is an odd one. Good thing he turns back to his 13-year-old self before his frantic mum answers the door.) In a further break with tradition, The Change-Up makes its protagonists wait until the next morning before reuniting them with the bodies they were born in.

Anyway, Bateman tries to tell his wife that he’s currently walking around in the body of his best friend. She doesn’t believe him, thus proving that characters in bodyswap films exist in a universe without bodyswap films. The whole trauma would be a lot easier handled if all you had to do was say “You know! Like in Freaky Friday!” This also explains why nobody in Albert Square ever wonders what’s on television during the Eastenders timeslot.

Curiously, Bateman and his wife have a special song (“The Dinner Song”), but Bateman chooses not to use it. Singing a song that’s only known to the protagonist’s best friend is a tried and tested bodyswap formula for getting your mates to believe the impossible has happened. This is fairly credible in Big (Josh and Billy seem like the sorts of kids who would have their own song), but using it in The Hot Chick means showing popular, cool teenager Rachel McAdams playing a clapping game with her friend in class like a special-needs eight-year-old.

It totally works though. It may be worth putting together a special song with your loved ones now in case this scenario ever happens to you in the future.

Bodyswaps also seem to happen at only the most inconvenient times. For months or years nobody has given a toss what you’re up to, but as soon as your big audition or Yale interview or promotion to partner in a law firm looms, you’re stuck in a different body and the biggest crisis of your life to date has to be improvised by your mum, your next door neighbour or your slacker friend. Luckily, sheer incompetence doesn’t seem to be a limiting factor: music careers are forged and places at Yale offered despite the protagonist’s behaving in a manner that should get them sectioned.

Nobody ever calls in sick when this happens either. If I ever wake up in the body of my daughter or friend or a random stranger I saw briefly at the gas station, I’m taking to my bed and staying there until the whole thing gets sorted out. Okay, I probably won’t be able to learn valuable lessons about myself and those around me, but to hell with it, at least I won’t have to furiously improvise during a deal-breaker negotiation with someone else’s boss.

In The Change-Up, Jason Bateman (with Ryan Reynolds’ mind) manages to secure a prestigious contract despite knowing nothing about his supposed job and consistently behaving in ways that would not only get him fired in the real world but quite possibly arrested. This sort of behaviour is usually happily overlooked in bodyswaps, because no-one wants to watch a comedy that ends with our hero desperately trying to piece together some semblance of his former life now that he’s out of work and his all his friends hate him.

But something of the sort does almost happen in 18 Again. Following a magical car crash (I may have forgotten some of the details), 18-year-old Charlie swaps bodies with his grandfather. Charlie then spends most of the film in a coma while his granddad gallivants around in his skin, excelling at sports, defeating bullies, getting the girl and generally making more of a success of his grandson’s life than the original owner managed to do. Some token attempt is made to show that lessons have been learned before the chaps swap back again and poor Charlie has to return to his radically altered life and live up to the high expectations everyone now has.

Far-reaching life lessons are the ultimate outcome of a body swap. In The Change-Up, Reynolds learns that family is important and a sense of self-worth comes from working hard and seeing tasks through to the end. Bateman learns to lighten up, take it easy and take better care of his bowels. Sadly unlike It’s a Boy Girl Thing, Reynolds and Bateman don’t use the holiday in one another’s bodies to discover their true feelings for one another and fall in love. Any Reynolds/Bateman snogging action that you’ve been eagerly anticipating will have to wait for another movie.

A month after the events of the film, the two protagonists of The Change-Up are shown together at Bateman’s anniversary party, their friendship strengthened, casually sharing a joke about Ryan Reynold’s penis and generally being better people. You’d think there’d be some post-traumatic stress after such an experience. How do any of these characters ever sleep again? I’d be terrified to ever close my eyes, haunted by the knowledge that the universe is a cruel and fickle place where horrific events can happen and you have no control over your own mind or body. Finally succumbing to sleep through sheer exhaustion only to jerk back awake confused and sweaty, frantically grabbing my private parts to reassure myself that they haven’t become someone else’s or disappeared entirely in the night. Or maybe that’s just me.