New concert dates were added the next day, but by the time Dad got through, again, all the seats were sold out. That night, the 37-year-old searched the Web for anything available in the area. He ended up buying four $30 tickets for a Thursday-morning show that would happen three months later in New Haven, Conn.–a two-hour drive away. “But it was totally worth all the hassle because the kids loved it, and we bought a ton of stuff,” says Katz. “Two T shirts, a stuffed big red car, two water bottles and the concert CD. I felt like I was on a Mastercard commercial.”

Playing hooky to take your ecstatic kids to a Wiggles concert: priceless. The Wiggles themselves: positively rolling in it.

If you haven’t heard of the Wiggles, you probably don’t have a 3-year-old anywhere in your regular routine. Over the last few years, the children’s band has become one of the most popular acts in kids’ entertainment, having sold more than 9 million home videos worldwide (6 million in the U.S. alone). Kids love them for their simple, catchy songs, sure, but they’ve also got a gimmick. Each of the four Wiggles has a signature color and a behavioral trait. Blue-wearing Anthony likes to eat, yellow-guy Greg performs magic, red-shirted Murray makes faces and purple-sporting Jeff falls asleep a lot. Kids love their sidekicks, too: Captain Feathersword, Dorothy the Dinosaur, Wags the Dog and Henry the Octopus. The music itself doesn’t go much beyond the toddler-friendly topics of food and animals. But it’s certainly struck a chord. Mention the song “Hot Potato” (the band’s biggest hit) to most 3-year-olds and you’ll almost certainly set them off spouting lyrics: “Hot potato, hot potato … Cold spaghetti, cold spaghetti … mash banana, mash banana.”

Yes, the band’s Australian, and no, they never considered changing their word choices to suit America’s children. “We say things differently, and they seem to accept that quite readily,” says bandmember Murray Cook, 42 (the guy in red). “They’re just learning about language anyway, so they can handle the differences.”

The Wiggles first came together in 1991 while three of them were studying early-childhood education at Sydney’s Macquarie University. They all loved performing music for kids and felt certain their sound would catch on. Not everyone agreed right away. “One famous booking agent told them, ‘Listen, there’d be no money in it for me and no money in it for you’,” recalls Paul Field, the group’s longtime manager (and brother of bandmember Anthony). But the Wiggles persisted, putting out a self-titled debut album with their own cash. Even more important than the CDs, however, were the self-produced home videos that followed. They filled a niche in Australia, where there were few such products for preschoolers. By 1995, the Wiggles had a series of videos, as well as four CDs, and in 1996 they made their first movie in Australia.

The money got bigger, but the band stuck to the system they had set up at the start. They shared all songwriting credits, the group (not a label) owned everything they created and royalties were evenly divided among the four. “We’ve read many books about entertainers who don’t own what they have created,” says Field. “It is scandalous. It’s like a real-estate agency calling and saying that they actually own the house they are selling for you.” The Wiggles continued to tour their country, put out CDs and videos and even developed their own TV series.

Toward the end of the ’90s, the group started thinking about broadening their brand. Their next move was obvious. “We had been going for so long in Australia, playing around the country so many times, doing the same tours over and over,” says Cook. “America was the Holy Grail.”

It’s hard to believe this now, but back in 1998, the four guys walked around Disneyland–one of their first stateside gigs–dressed head to toe as the Wiggles, and no one recognized them. The next year, they got an opportunity that opened a lot of doors: their promoters, HIT Entertainment, added them to Barney’s live tour as the intermission band. With parents always searching for children’s music that’s even remotely tolerable, word spread quickly. By 2001, most American parents were well-aware of the Wiggles. Their videos and CDs grew popular and their concerts usually sold out. Then in the spring of 2002, the Disney Channel picked up episodes of the Wiggles’s Australian TV show. That’s when appreciation of the band set in outside the potty-training set. Last fall, the producers of CBS’s “Yes, Dear” wrote an episode around the Wiggles, and that same month they were included in perhaps the most American kid tradition of them all: Macy’s Thanksgiving Day parade. Of the $8 million the band earned in 2002, half came from the United States.

The Wiggles are now set to conquer the rest of the world, too–and they have an ingenious plan for doing so. The band has a licensing deal with Walt Disney International for Asia to cast new versions of themselves to tour in other countries. That means that not only could they be in two places at the same time, they could hypothetically be in 10 places at the same time.

The first clone of the group was created in Taiwan, where they’ve added a twist: the red Wiggle is a woman. They’ll do a Taiwanese TV show and record the songs, just like the Australian originals. “The Wiggles can’t possibly service each of these markets, particularly those that are non-English speaking,” says Mike Conway, the band’s business-affairs manager, who joined the team in 2001 and who was intimately involved in the deal with Disney. Another set of auditions will be held this month in Japan, to be followed by similar castings in Korea, Thailand and China.

It’s not hard to imagine the Wiggles turning into a billion-dollar empire. “Mostly we sort of laugh at it,” says Cook. “We’re not really businessmen, we’re just musicians and entertainers and teachers. We’re from that background.”

And for a band with an increasingly global reach, indeed, that’s what it all comes down to: the Wiggles’s personal connection with the kids in their audience. Take little Hannah Edelman, for instance. She so adores them that for her third birthday party last year in Cleveland, her parents threw her a Wigglesfest. All the adults dressed in colored shirts like the four guys. The balloons matched. And Mom and Dad printed a bunch of pictures off the Wiggles Web site and had them enlarged. “Various Wiggles tapes were on the TV the whole time, and we had maybe 20 adults there. Lots of them probably went out to buy more of the videos,” remembers Shelly Plasco, Hannah’s grandmother. “We probably drummed up a lot of business for them.” Thanks, Grandma Shelly. We’re sure they appreciated it.