At one point during a family dinner, sitting at the table with mom, dad, grandparents and twin sister, out of nowhere young Henry Focker asks whether girls poop from their vaginas. Aside from wondering why a five year old boy even knows the word vagina let alone what it is, I’m not sure which is more depressing. What his question says about the teaching of human biology in American primary schools or that this is the level of wit to which this once briefly funny franchise has sunk?

But hey, if that had you splitting your sides with laughter, you’ll be in hysterics when young Henry catches dad Greg (Ben Stiller) in the toilet injecting adrenaline  into Grandpa Jack’s (Robert DeNiro) erect penis. The two men look profoundly embarrassed. Unfortunately, that’s in character, not a response to being in the movie.

Set some years after Meet The Fockers, Jack and Dina Byrnes (Blythe Danner) are visiting Greg and Pam (Teri Polo) in Chicago for the twins’ birthday. Getting on a bit, Jack’s been having some heart problems which have caused him to ponder who’ll take over the circle of trust when he’s gone. Certainly not Dr Bob, no longer his son-in-law after he was caught having an affair and got divorced. They’ve had problems in the past, but could Greg be up to becoming the Godfocker?

Now a head nurse, Greg’s keen to prove he has what it takes, but, looking to make some extra cash, rather unwisely agrees to help sexy sales rep Andi (Jessica Alba, who won  the Razzie for Worst Supporting Actress) push a new Viagra-like drug and has, naturally, got a case full of samples stashed in the house. At this point, no one else knows Andi isn’t an Andy. Can you see where this is going, yet?

Director Jay Roach wisely jumping ship for the third installment and handing the doomed vessel over to Paul Weitz, the screenplay lazily recycles all the same gags and routines from the first two films, Jack spying on Greg, Greg putting his foot in it, the same ‘trust’ issues, any number of ‘hilarious’ misunderstandings and, thanks to the twins, plenty of  opportunity for that sidesplitting projectile vomit moment. And, just to prove you can flog a dead horse, there’s even another gag about Greg’s surname!

But, what about the other characters and the cat, you ask? Fear not. Mr Jinx manages to gratuitously make an appearance when rich bland hippie Kevin (Owen Wilson) turns up, bringing her with him. Finding he couldn’t wriggle out of things, Dustin Hoffman did at least manage to cut his scenes down to the minimum, most of the plot shunting Bernie off to Spain where he’s bizarrely gone to study flamenco dancing. Clearly with less concern about her dignity, Barbra Streisand was only too willing to return as Roz, presenting a TV sex show and advising Dina about kinky role play to spice things up with Jack. Did I mention that erectile-dysfunction drug?

Laura Dern manages to squeeze a laugh out of her snooty private school headmistress, but Harvey Keitel must have had serious cash problems to agree to the agonisingly unfunny role as the contractor building the new Focker house. At one point he and De Niro get to trade inane insults. It’s like Mean Streets and Taxi Driver never happened.

Released on Paramount Home Entertainment, to be fair, there are a few genuinely amusing moments (De Niro and Still battling in a bouncy castle and ball pit) and, given the the alternate opening, ending and deleted scenes it could have actually been worse; but if you’ve ever wondered how bad any film can be in which Jessica Alba strips to her undies and rolls around in mud, then here’s the answer.