But now, with Obama in the White House and combat forces pulling out of Iraq, the name takes on a new meaning. It cannot be a coincidence that the poster shows the star with a strip of police tape marked Danger over the lips. Williams has spent the last 30 years making self-destructive decisions.
Not that World's Greatest Dad was one of them. In the film he reins in the twinkly eyes and funny voices, and is utterly convincing as the charmless high school poetry teacher who exploits the death of his vile porn-hound of a teenage son. Williams' desperate need for audience approval, so cloying in other contexts, works brilliantly here as his character is also seeking love and appreciation, usually in vain.
World's Greatest Dad is directed by Bobcat Goldthwait, a stand-up comedian friend of Williams. The 59-year-old star, who won an Oscar for his role in Good Will Hunting and can command top Disney dollar for putting his rubbery vocal chords to their animated characters, initially agreed to a cameo role, to help his chum get the movie off the ground.
"I took it initially as a favour to Bobcat, thinking that if I played a small part maybe it'd get financed," he said recently. "Then I read it and went, 'Would you mind if I played the main character?' He's a really interesting, awkward, damaged guy, and the subject matter is so powerful. I think the title catches people, they think it's going to be goofy. But if you've seen any of Bobcat's other work, you'll kind of know what to expect. I mean, in his last movie a girl blows a dog."
In real life, as well as in his posters, Williams could often use a piece of police tape over his cake hole.
But it is this very orifice, with its wild ad-libbing and vocal schizophrenia, that first brought Robin McLaurim Williams to the world's attention. After acing his dialects class at Juilliard, the young graduate was cast as Mork, an alien with unfortunate taste in rainbow braces, in the TV series Happy Days. His zany improvised dialogue and parmesan-grating nasal accent led straight to a spin-off series, Mork & Mindy. This ran from 1978-82 and put Williams on network television, to say nothing of colouring books and lunchboxes.
Then, for the grown-ups, there was Williams' stand-up, a frenetic fry-up of characters, impersonations, personal confessions and plain old filth. ("When in doubt," goes one of his regularly quoted lines, "go for the dick joke.") Piggybacking on Mork's alien shoulders, Williams fast-forwarded past the college-toilet tour and went straight to prestigious venues where his shows were also recorded for television specials.
At this point, Williams kept the self-destructive behaviour for after hours. He met Valerie Velardi, an actress and dancer working as a waitress, in 1976 at the Holy City Zoo comedy club in San Francisco. They married in 1978. The newly famous Williams spent a lot of time with notorious party animal John Belushi and shared his taste for booze and cocaine ("Cocaine: God's way of telling you that you have too much money").
Williams visited his friend at the Chateau Marmont hotel in Beverly Hills the night he died after taking a cocktail of heroin and cocaine known as a speedball. He later said it was Belushi's death, and the birth of his son Zak the following year, that prompted him to stop drinking and taking drugs. "Was it a wake-up call? Oh yeah, on a huge level. The grand jury helped too."
His marriage to Velardi was soured by a series of what Williams himself admits were outrageous affairs, including one with a cocktail waitress which ended in a lawsuit over a herpes infection. Yet during the 1980s, while all this was happening, he ceased to be the guy who used to be Mork and became an international film star. Good Morning Vietnam was his breakthrough role with Williams playing, as he would go on to do so often, a version of himself. This one was an abrasive forces radio DJ who enchanted the troops with his outrageous accents and hilarious ad-libs. The part gave Williams an Oscar nomination and a Golden Globe.
Throughout the 1990s, Hollywood offered Williams many outlets for his singular talents. Some parts, such as the reprobate father who drags up as Mrs Doubtfire to keep in contact with his children, were a perfect fit. Thanks to Williams' work in the soundbooth, the genie in Disney's 1992 version of Aladdin flooded the film with adult references, in-jokes and gentle smut that swam over the heads of the young audience but stopped their parents from sinking into a popcorn-induced torpor.
In 1997 he won the Oscar for Best Supporting Actor for his role in Good Will Hunting. Yet his other three films that year were Fathers' Day, Deconstructing Harry and Flubber. Williams appeared to have an answering machine that simply played the message "Yes". Patch Adams was a career low.
"That's what they were offering, and it's very hard to convince people to offer you something else," he said recently. "I was paying the bills, and they were offering shitloads of cash. They dangle big money in front of you and go, ‘You want to do this?' Yeah! Sure! And you end up driving it into the ground."
Yet slowly, over the last decade, the self-destructive behaviour has tailed off. His second marriage, to Marsha Garces, started in a tabloid firestorm - she was his son's nanny and several months pregnant when they wed - but lasted 19 years. Roles in credible movies such as Insomnia, One Hour Photo and now World's Greatest Dad, have reminded the world that he can do more than twinkly and goofy. After a three-year fall off the wagon he stopped drinking for the second time in 2006. Last year's heart surgery - his own aortic valve was replaced by one from a pig - has left him, when he can stop showing off with the dick gags and racoon impersonations, profoundly glad to be alive.
It is just possible that the man who has made an estimated fortune of $130 million from self-destructive, childish behaviour has finally grown up.
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• Robin Williams was born in Chicago, to a former model and a Ford motor company executive. The family were Episcopalians. He is still a member of the church, describing it as "Catholic Lite: same rituals, half the guilt".
• One of his classmates at Juilliard was Christopher Reeve, right, the actor who went on to play Superman.
• His family persuaded him to check into a rehab clinic in Oregon in 2006. "I went to rehab in wine country just to keep my options open," he said, but still attends AA every week.
• He relishes a good baddie. "Playing evil is seductive because you can explore behaviour that in real life you'd do prison time for. Most nasty f***ers are very charming."
• Williams is a keen gamer and named his daughter Zelda after the princess in The Legend Of Zelda video game. In 2006 he took part in Worldwide Dungeons and Dragons Day.