BBC World Service Arts correspondent Lawrence Pollard joins The Wiggles
By Lawrence Pollard
World Service Arts Correspondent
The Wiggles are an unusual global phenomenon.
They are seen on stage by 750,000 fans each year, they recently sold out Madison Square Gardens in New York for 12 consecutive shows, and they have sold 30 million DVDs and CDs.
Their TV show is available in nearly 50 African countries and throughout the Middle East.
But Anthony Field, Murray Cook, Jeff Fatt and Sam Moran who make up the blue red, purple and yellow Wiggles, may have completely passed you by - especially if you are over five years old.
It is their simple pop sing-a-long songs that have helped make them such a big hit.
"We play the pop, early 60s style we used to play in our previous band, the Cockroaches, but with different lyrics," says Cook (Red).
"In rock and roll, the songs are mostly about love, but with children you can write about anything.
"A ride in the car, what you're going to eat - it's quite limitless so you try to think what's in their world, what interests them. Everything's exciting to a young child."
That might help explain their song Fruit Salad then.
They are Australia's most successful entertainers and make more money than pop sensation Kylie Minogue or Hollywood actor Russell Crowe.
The group spend half the year on tour - and have just arrived in London to meet some young fans.
They regularly perform in front of 12,000 fans, But for the BBC, they sang to just 20 two-year-olds.
With no props and lighting, they were just four entertainers doing their job.
"This is harder work than doing a big performance," says Fatt - the purple one.
"You can see exactly how much attention you're getting."
Cook and fellow founding Wiggle Field (Blue) met while they were studying to be pre-school teachers.
Their classes in child development and education have, they say, completely influenced their way of writing a song.
"You have to marry movement to the music so children own the experience," says Field.
"So the song Hot Potato, with its very simple hand movements, means they own the song as opposed to just sitting and listening.
"Children learn through doing - and also we learnt that you need a reason for a song.
"So a song for singing has to have the few notes a child can manage at that age.
"A dancing song can have a more complex melody, so there's different reasons for doing a song. They don't just happen."
The Wiggles spend half the year touring
Moran (Yellow) completes the foursome. He replaced original band member Greg Page, who retired in 2006 suffering from a chronic medical condition.
The Wiggles are at the centre of a huge entertainment brand, which they control and release an album a year - at least.
Then there are their videos and tours - which are usually big, colourful production with dancers, effects and cartoon characters.
So how do they find young audiences differ round the world, performing from China to LA?
"Mostly they're the same," says Murray.
"I think a lot of the cultural differences are learnt at a later age than our audience.
"Even if they don't speak English, audiences respond in very similar ways."
The foursome say that being relentlessly upbeat for an audience of kids for months at a time is not hard work. Instead it lifts them.
They claim to be "just a bunch of Aussie dags", or "geeks".
But just occasionally their day job throws up some weirdness, worthy of the wildest rock n roll band.
"I broke my wrist on stage," says Field. "We have a huge dog bone for a prop and it fell down.
"Stupidly I put out my hand to catch it. It was huge and it snapped my wrist.
"So I went to the hospital and the two people in front of me had gunshot wounds. I had to tell the doctor what had happened and he said it was the most unique injury they'd seen that day.
"A giant dog bone. Very rock and roll, or maybe Spinal Tap," he jokes.
For people meeting the Wiggles, giant bones are not be to wary of. Just a limited exposure to the band will result in you humming their tunes rather longer than you might wish to.
The addictive riffs for the underage are written deliberately to stick in your mind - and they do.