Symptoms include relentless self-parody, courage in the face of mockery and making a pile out of hamming it up. The latest illustrious patient is none other than the curvaceous Monica Lewinsky. The girl with the Botticelli bottom is discussing a multi-million dollar contract with an Italian film company to star in a sexy comedy romp.
On the small screen, football veteran Ron Atkinson and Seventies heart- thumper Lewis The Professionals Collins jumped at cameo send-up roles in the cult TV series The Grimleys. And in ad-land Henry Kelly, Bonnie Langford and Countdown's Richard Whiteley have all appeared in the Asahi beer campaign looking urbane, sophisticated and comfortable in the knowledge that their naffness was the punchline.
Meanwhile, Vinnie Jones is set to make another killing out of his hard- man image. Following the success of his, well, hard-man performance as Big Chris in Lock, Stock and Two Smoking Barrels, he's just landed a lucrative role playing a character called "Spinx" opposite Nicolas Cage in the new Jerry Bruckheimer movie. With a name like that, Vinnie's not likely to be playing against type.
But when it comes to the naturals, nobody does it better than Christine and Ian Hamilton. They've cornered the market in sending up the middle classes, Mr & Mrs, the Conservative party and themselves in one. They've appeared on Have I Got News For You, presented The Top Ten Scandals for Channel 4 and are set to be guests of honour at an Oxford University Association dinner because it wanted a "more entertaining sort of guest". A solid career in self-mockery, it seems, stretches before them.
Don't they feel the least twinge of pride? "After the election we both lost our jobs and our incomes," says Christine. "Now we are 'professional objects of curiosity' rather than celebrities. We found the ability to laugh at ourselves very important over the last few years and we've both found the media a fun field to work in. If you can't laugh at yourself, you're going to find life fairly tough."
So why are celebs doing the self-parody thing? Well, first, tastes have changed. Irony still has a vice-like grip on pop culture, and if you can't take the mickey out of yourself you're in trouble. Then there's our blase reaction to scandal. The days when government-toppling temptresses retired in shame have long gone. Christine Keeler was always a sulker, but if the Profumo affair happened now, Mandy Rice-Davies would have landed a record deal, a bra campaign and a TV show before the War Minister's head hit the House of Commons floor.
"Humour is a great way to win friends and break down barriers," says PR guru Max Clifford. "Monica Lewinsky has come in for a lot of attack, and to be seen to send yourself up is an act of humility and humour that a lot of people would potentially find endearing. We as a nation like people that are not seen to take themselves seriously."
Monica has realised she could do worse than indulge in a little self- parody, and she's going by the rule "laugh at yourself before others get to". In America the woman's obviously not popular, and if she so much as ventures down to K-Mart without an armed guard she's likely to be pelted with root beer cans. Money gets you privacy, and how better to earn it than first spill the tears, spill the beans and then ruthlessly send yourself up? After all, if she doesn't there's a queue around Capitol Hill of people who will.
So, who will be the next to join the self-parody gang? Perhaps we can look forward to Lady Thatcher's TV show, One Woman And Her Handbag, where she rounds up nanny-wet Whips with an oversized Kelly bag. Or perhaps we'll see Men Behaving Strangely, where Glen Hoddle and David Icke will communicate only by telepathy and lay healing hands on lucky guests.
Whatever happens, there is a lesson to be learned from a celebrity's self-parody. Tara Palmer-Tompkinson, the girl with a plum in her mouth and a tongue in her cheek, is "resting" in an Arizona addiction clinic after she sent herself up a little too well on TV. It seems that there can be such a things as too much self-parodying, especially when it's done on The Frank Skinner Show.