Representing a career low for the star-producer of Battlefield Earth and a comedian who hasn't made a memorable appearance on screen since 1993 (and that was Mrs Doubtfire), Old Dogs is a remarkable achievement.
A big-screen rip-off of TV hit Two And A Half Men, it stars Travolta and Williams as Charlie and Dan, two lifelong buddies about to land a multimillion dollar marketing contract with a Japanese electronics giant.
To win over their inscrutable clients, Charlie recalls the occasion when, seven years earlier, Dan went to Florida to celebrate his divorce, got drunk, and woke up with a rib-tickling tattoo and a new wife, Vicki (Preston).
The Japanese find this hilarious. Later, they show just how not-inscrutable they are by laughing themselves to tears when Charlie pulls a silly face and making a key business decision based on the email message "Sony is poop" (this is a Disney movie, so nerrr).
Anyway, lovelorn and humiliated, Dan receives a boost when Vicki suddenly arrives in New York with her twins Zach (Conner Rayburn) and Emily (Ella Bleu Travolta). And guess what? He's their dad!
Sadly, Vicki has to go to jail for two weeks. But when her best friend (Rita Wilson - sole comic contribution: going cross-eyed) is hospitalised, it's time for Daddy Dan and Uncle Charlie to get responsible.
And so the fatherly fun begins, with misadventures at scout camp, the tanning salon, the golf course and the zoo interspersed with mishaps involving prescription medications, a society of bereaved women (?!), and a gadget that turns Dan into a remote-controlled puppet.
On top of the constant irritation of Seth Green as Chaz and Dan's office suck-up, each hopelessly contrived episode comes with its own pointless cameo.
At least Travolta's wife and daughter (Preston and Ella Bleu) can say they did it for love. But how Matt Dillon, Justin Long, Luis Guzman and the usually dignified Ann-Margret got sucked into this mess is a mystery.
And as for poor Bernie Mac, he deserved a better epitaph than this. "How bad is it?" asks Williams at one point. "Bad" says Travolta. The script speaks for itself.
A slapdash embarrassment of feeble age gags and cultural stereotypes, Old Dogs is at once crass, corny, amateurish, insulting, uninspired, deeply phoney and extraordinarily unfunny.
Do the humane thing - put it out of your misery now.