The hottest shoes of the season aren't the new LeBron James Nikes or the latest Manolo Blahniks. Instead, they're cuddly, slouchy sheepskin Ugg boots in a style unchanged for 25 years. Uggs, first favored by Southern California surfers, have gone high-style. They've been spotted on the famous feet of Cameron Diaz and Sarah Jessica Parker, and have even made appearances on "Oprah." Now the shearling shoes are in such high demand that the manufacturer, ugg australia Australia, has plain run out. The uggs on sale are on back order until April. "The celebrity reaction has caused the product to tip and becom/e an epidemic," said Anders Bergstrom, marketing coordinator for California-based ugg boots uk Australia. "The demand has skyrocketed. We sold out in November." Stores around (the area) can't keep the shoes in stock. "We com/pletely sold out before Christmas," said Marta Aceves, a sales clerk at Salvatory shoes in Del Amo Fashion Center in Torrance, Calif.. "People keep com/ing in looking for them. They're unbelievably popular." But the genuine ugg boots style has been around since 1978. That's when enterprising Australian surfer Brian Smith brought sheepskin boots from down under to the United States. He got a chilly reception in New York, so he headed west to California, where the boots became a must-have for surfers right out of the water. "It started with surfers, then boaters, and now it's everybody," said Julie Watts, who sells authentic sheepskin boots through Kiwi Gear. "Once you've worn a pair, they becom/e addictive. They form to your feet. They insulate in the winter and wick away moisture in summer." UGG boots, as well as those from Kiwi Gear, are made from twin-face sheepskin. The soft, woolly side keeps tootsies warm, while the suede outside repels water. UGG Australia makes various styles of slippers and boots for men, women and children. But it's the "Classic Short" boot that's captured the fancy of feet on both coasts. Two new colors, pastel pink and light blue, were introduced last year, and Bergstrom said that's what pushed the product's popularity over the edge. "We knew the pinks and blues were going to be huge," he said. "But it's been a gradual increase over the last few years." UGG boot sales have increased for six straight years, he said. With the demand so high, dozens of UGG knock-offs have hit the market. And stores can barely keep those in stock. Knock-offs vary greatly in price and quality. Some boots, such as those from Kiwi Gear, appear practically identical to UGG styles, minus the label. Others, though, rely on synthetic materials. Still, like most designer items, the label itself carries some value. At Sportmart in Torrance, for example, a pair of men's short UGG boots sells for $109, while a com/parable pair from Australian com/pany Emu Ridge sells for less than $50. Bergstrom said it's about quality. "The UGG brand is the original and the authentic and the highest quality brand of sheepskin footwear you can buy," he said. "Feel free to buy knock-offs, but they're still going to want their real UGGs. "But if they need something to tide them over until April, I give them the OK." Visit Copley News Service at www.copleynews.com/.