The famous phrase started by accident. Michael Eisner and his wife dined with Dick Rutan and Jeana Yeager, a duo who just became the first to fly non-stop around the world. Asked what they planned next, Rutan deadpanned, ""I'm going to Disneyland." After a good chuckle, Eisner's wife Jane said, "You know, that's a good slogan."
With Super Bowl XXI rapidly approaching, Disney acted quickly. They looked at both teams and tried to determine MVP candidates, eventually zoning in on the two starting quarterbacks: the Giants' Phil Simms and the Broncos' John Elway. Since it was the first time The Mouse had to front some guaranteed cash, Simms got $75,000 win or lose (if he said it or not), while Elway was offered less (at least $15,000, though possibly almost $50,000). Simms' Giants demolished the Broncos — as he jogged off the field in victory, a tap came on his shoulder. "Disney!", the voice shouted. He almost forgot about it, because after 60 minutes of football and visions of championship glory dancing in your heads, a random ad spot is furthest from your mind. But he said the line, and created a tradition.
The famous slogan (and payday) bled into other sports and cultural events. Disney, who's as much about marketing as it is about magic, quickly got wise, and had every player (even the scrubs) sign a contract to say the line — this way, they could assure they'd get what they needed, no matter who won. It also helped them not use the Ravens' Ray Lewis — he was the MVP of Super Bowl XXXVII, helping his team cruise to a 34-7 win over the Giants, but due to his alleged involvement in a double murder the year prior, Disney had no interest in him. Quarterback Trent Dilfer got pegged to say the line instead, because the only murder he had anything to do with, was that of the Giants' hopes and dreams.