This screwball romp has a healthy share of belly-laughs and even some “aw shucks” sentimental moments. But with less of the offensive, frankly jarring scenes, they could have made a movie reasonably reliable for family viewing. Sadly, at times We’re The Millers teeters uneasily into territory that should really be out of bounds.

One of the scenes in question occurs quite early on and involves a seedy cop who is looking for a bribe, or otherwise a sexual service involving an 18-year old boy. It’s not funny, but the scene ends with a deft avoidance of the actual service. The audience only begins to breathe again after this squirming encounter ends.

And the testicle bitten by the tarantula isn’t funny either. This scene cynically buys into the YouTube humiliation fad - that context has already been established - and, of course, the testicle clip goes viral. One immediately docks two stars for such a cheap shot at knowing, streetwise comedy. Just because it's faddish doesn't make viral humiliation valid for entertainment, simple as.

But aside from that, We’re The Millers is laugh-out-loud brilliance, smarter and sassier than films it might vaguely remind you of, like Meet The Parents or Meet the Fockers. In a film which is obsessed with sex, one of the funniest scenes takes place in a tent and involves high jinks amongst four adults, two of whom may not be as consenting as they appear.

As the story begins, likable David Clark is a small-time pedlar of soft drugs in Denver, Colorado. After a street fracas, he is robbed of 20 thousand dollars profit he was about to deliver to his sleazy drugs boss, Brad (Ed Helms).

Brad duly forces David to take a trip to Mexico to smuggle drugs he has no alternative but to agree, as he owes his boss 20 grand. Plus he stands to receive a handsome pay-out himself. Brad assures him that he has but to collect a small amount of marijuana in Mexico. But, hey, that’s a lie.

It dawns on David that he must assemble a neat all-American family – The Millers - as the perfect cover. Rose (Jennifer Aniston) lives in the same apartment block and works as a stripper. When she finds herself out of a job, she reluctantly agrees to join David on the trip, pretending to be mom Miller.

The couple are joined by a teenage runaway, Casey (Emma Roberts), who for a fee, will play the daughter. Completing the brood is the goofy, lovable Millers’ son, Kenny (Will Poulter). The ready-assembled family pile into an RV, which David acquires for the trip.

Much of the humour derives from the fact that the Millers fail to function as a normal family when that is clearly what is expected of them, when they interact with other folks.

On the other hand, when the Millers begin, despite themselves, to resemble a real family after time spent cooped up in the RV, their clumsy affection for - and loyalty to - each other tugs at your heartstrings. Which is really quite clever, as it ends up being a feel-good movie as well as a comedy, and both Aniston and Sudeikis are on top form.

Go see, but be prepared for occasional gross interludes which the film could have well done without.

Paddy Kehoe