Forget Britney Spears and Cirque du Soleil. For many gamblers, the hottest attraction in Sin City is an outdated three-reel slot machine that hasn't produced a jackpot in nearly two decades.

It is called the Lion's Share, and in this city with no shortage of losing bets, the 20-year-old slot has attracted a legion of ever-hopeful devotees on the floor of the MGM Grand, the Strip's second-biggest casino.

The machine's miserly track record may, paradoxically, make it the rarest of all Vegas treats: A decent bet. A generation of players has already lost money on it, helping more than double the progressive jackpot to an improbable $2.3 million.

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"You see the sharks swimming around, scoping you out," said Washington state resident Lief Anderson. The 64-year-old is a second-generation Lion's Share player: He took over the family quest from his late father 10 years ago.

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According to long-established slot etiquette, the seat is first-come, first-serve, and the player can stick around until he is exhausted or out of money—or both. On a $3 maximum bet (the machine takes $1 and $2 bets, too) a player can earn up to $10,000 without hitting the jackpot, and small hits can keep someone in his vinyl seat for many hours.

At 23, Justin Paulus is barely older than the machine is, but the engineer is so committed to taking his shot that he fell asleep at it repeatedly during a six-hour overnight session last spring.

"Security kept coming over to wake me up, but they didn't say I had to leave. So I'd wake up, press a button, and then fall asleep again," said Paulus, of Chandler, Ariz. "I just have this feeling it's going to hit soon."

On a recent weekday morning, Karen Kuefler, 50, was dragging on a cigarette as she sat at the slot, instructed by her husband not to let anyone else cut in. "If he could sleep with this machine, he would," the Calgary resident said of her husband.

Her husband, Ken, a 51-year-old boilermaker, said he brings up to $5,000 each trip for the machine, and won't put a cent in any other machine. "It's become a meeting spot for us," he said. "We have friends we've made just from waiting at the machine."

Even by the standards of slot enthusiasts—known to be an obsessive and superstitious lot—the Lion's Share has a devoted following. The machine has its own Twitter account, Facebook profile, fan websites and message boards. Each sight of one lion, which pays $6 on a $3 bet, is considered breaking news. The machine is the oldest three-reeled slot in the property and has the highest level of "occupancy," or daily time played, of all 1,900 of the casino's machines, said Justin Andrews, the MGM's executive director of slots.

A turn at its seat, located just outside the casino's Grand Wok and Sushi Bar, can inspire strange behavior. Some players will only pull the old-fashioned lever on its right side, some hit the "spin" button with their feet, and others execute elaborate choreographed rituals before every play.

"I'm not normally like this, but with this machine, I talk to it. Whenever a lion comes up, I rub it. I know it's strange, but the machine has this juju about it," said Siubhan Pabst, 34, of San Jose, Calif.

This past summer, she lined up two lion icons in a row, then barely missed the third. She won $10,000. "I was sitting there at the machine frozen in shock for 20 minutes," she recalled. "After, I was on this crazy high for two days."

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