Would alarm bells ring over the slightly roguish, Oscar-nominated actor who swings between stoner comedies and arthouse curveballs?

Quite possibly.

In any case, in Why Him? Franco comfortably inhabits the role of an alarming boyfriend in the character of Laird Mayhew, a shirtless, foul-mouthed fool.

The arrival of a less-than-desirable suitor is the premise for the festive comedy that teams Franco with Bryan Cranston, who plays Ned Fleming, a father stricken with horror at the prospect of a degenerate, billionaire Silicon Valley whiz-kid dating his daughter Stephanie (Zoey Deutch).

And yes, at first glance, Franco as Laird is every father's nightmare. He greets the family for the first time as they come to visit at Christmas with all the decorum of: "The motherf---ing Flemings are in the house!"

It's a bracing introduction, to say the least.

Then there's his dinner table conversation about a sexual encounter in a spa, and his decision to get a full back tatt featuring the Flemings' Christmas card portrait.

"No father would want their daughter with this guy," says a simmering Ned.

Why Him? is a bawdy slapstick comedy that considers contrasts and clashes across generations.

"You don't seek parental approval in the same way [these days]," says 38-year-old Franco. "In Bryan's day he said you'd have to show up at the door and [spend] a bit of time on the couch downstairs, and you're waiting for your date to come down and being interrogated and sweating bullets. I never really had that."

It's not the first time  Franco has been up against Cranston. The pair made In Dubious Battle together last year – an arthouse drama directed and produced by Franco and based on the John Steinbeck novel about a fruit-pickers' strike in the 1930s.

Next year they're both in The Masterpiece, again directed and produced by Franco, about the making of the cult hit The Room, widely regarded as the worst movie ever made. Set in the early 2000s and Cranston plays himself, cresting the wave of his fame from the darkly rich family sitcom Malcolm in the Middle. 

Cranston's critically acclaimed, career-defining role as Walter White in Breaking Bad aside, Malcolm in the Middle is him at his comic best, as the permanently exasperated father Hal, grappling fruitlessly, impotently with a world out of his control.

Ned is not a big a departure from Hal – the pair share the same blood-vessel bursting levels of frustration and despair that Cranston channels so well.

To get a sense of the humour of Why Him? one needs only to look at its pedigree. Ben Stiller's company Red Hour Productions is the producing power behind it alongside Shawn Levy, the mastermind behind this year's Netflix hit Stranger Things.  

It's directed and written by long-time Stiller collaborator John Hamburg, whose writing credits include the Zoolander films, Meet the Parents (2000) and its sequels Meet the Fockers (2004) and Little Fockers (2010).

Why Him? is a kind of updated version of the Fockers films and the familiar story of a family at loggerheads.

Will & Grace's Megan Mullally is Barb, the mother Fleming, a more open counterpart to the uptight Ned; 15-year-old son Scotty (Griffin Gluck) is also part of mix. He shares Laird's entrepreneurial bent.

Cranston says Hamburg brings to the film a truthful take on conflict, both generationally and economically.

"There's a level of real honesty to it," he says. "That there are people who are this way, who have free rein of language, who are dealing with different socio-economic status like the Silicon Valley tech moguls who are young and aggressive and assertive and pushing forward with new ideas. It's the new ideas versus the old-school ideas."

The story itself was sparked by actor Jonah Hill, who, while filming The Watch (2012) with Stiller, told its producer, Levy, about his experience with his new girlfriend's family.

"Jonah had recently started dating Dustin Hoffman's daughter [Ali]," says Franco.

"He went on vacation with Dustin's daughter and the rest of the family, and they'd only been dating for a very short amount of time, and so he came to set and was telling that story to Ben and how worried and nervous he was.

"Dustin's a great guy and it ended up being fine; it wasn't like Dustin was trying to get rid of Jonah or anything. But that's how it started, how awkward it was to have to go on vacation with your girlfriend's family when you didn't really even know her that well and I guess Shawn, being the master producer that he is, just heard that and was like ah-ha!"

For Cranston, as the father of a daughter, 23-year-old actor Taylor Dearden, he must be familiar with the trials and tribulations of being a protective father facing potential boyfriends.

"You know, there's always a handful [of things] that you're not going to like about your children's decision-making, just like the same thing that your parents felt about you," he says.

"It's this cyclical kind of situation where we realise that our parents messed us up and we realise, with all the best intentions, we're going to screw up our kids [too] somehow, some way.

"But as far as personally, I hope that the boyfriends and the guys that she meets will treat her well. That's really the only thing I care about – be kind. The rest, whether or not it works out or [becomes] love or whatever, if you start with that then that's the best."

A lot of the conflict for Ned, Cranston says, is the jarring gap between expectations, wanting that fantasy son-in-law addition for the family Christmas card, and reality.

"Laird doesn't represent the guy that he imagined in his head would be dating Stephanie," he says.

"I imagined a young law student or something like that, that they have something in common, that they share a sense of charity and social awareness and those things, and he comes from a good family. You know, the picture-perfect kind of situation.

"And whenever we think of what is the picture-perfect situation, I think god, or whomever you believe it to be, steps in and says 'Oh well then, how are you going to feel about this?' You have some life lessons."

A character as vulgar as Laird does throw up the conundrum of how to keep an audience on side. The challenge was to show that Laird has the best of intentions.

"If we made him good at his core," says Franco of tackling the problem, "That he truly loves Stephanie – as crude and as unfiltered as he is, underneath that he's completely honest and so clear about his love. If we establish that and everything that he does, no matter how obnoxious it is, we really wouldn't go too far if we don't betray that."

As the film goes on, it becomes a learning curve for everyone in reconsidering their own behaviour and judgments, not least for Ned who can't see anything other than Laird's unpleasant behaviour, says Franco.

"It blinds Ned to the goodness underneath because in fact the character is everything that Ned wants for his daughter, he just can't see it because the surface is screaming so loudly in his face," he says.

Interestingly the film, despite not being released yet, has already come under fire over claims of sexism and misogyny. Critics have said pitting two men in battle against each other over a woman depicts Stephanie as a mute chattel, not a person.

"We worked hard to imagine what the audience would want at the end of the movie," says Cranston. "And that is these men have been fighting each other over this woman – and she has her own right, she's not a possession, she's not a piece of property.

"She is an individual and an independent thinking and feeling woman, and she got pissed off at them because they weren't giving her the right to speak her mind."

As a festive offering, the film offers much in the way of fun, but Cranston says he hopes it reaches deeper than that.

"I hope first and foremost  that it's entertaining, that people will laugh their asses off. But underneath that, those laughs will be more meaningful if they also come away with a sense of satisfaction, that they enjoy the ride and it wasn't just one joke after another, that they really cared about these characters – they wanted to see them succeed."

Why Him? is out on December 26.