Courtesy of SI.com:
Mike Tice: The Vikings got off to a rousing 6-0 start in 2003, but the chorus of doubters became louder after three straight losses. Perhaps trying to replicate the success of Giants coach Jim Fassel three years earlier, Tice publicly proclaimed that his team would make the playoffs. Alas, while the '00 Giants won their last five regular-season games en route to the Super Bowl, Tice's Vikings ran aground. They dropped their next game after the promise and went 3-4 down the stretch to finish 9-7 and out of the playoffs.
Lou Piniella: Sweet Lou's Mariners won an AL-record 116 games during the 2001 regular season. The historic season was suddenly in jeopardy, however, when the Yankees swept the first two games of the ALCS in Seattle with three games looming in the Bronx. That's when Piniella guaranteed that the series would return to Seattle for Game 6. He looked like a soothsayer when the Mariners crushed the Yankees 14-3 in Game 3. But New York won the next two games to close out the Series in five games, with Yankees fans chanting, "No Game 6! No Game 6!"
Patrick Ewing: He issued more public guarantees than the Men's Wearhouse guy. Unfortunately, the value of his assurance was more savings-and-loan than FDIC. A true triple threat, Ewing issued pledges during the preseason, the regular season and the playoffs. Among his most famous predictions was "I'll see you Sunday" in 1995, meaning that the Knicks would beat the Pacers on the road in Game 6 to return home for a Game 7 that Sunday. (The Knicks did win Game 6 but lost the deciding game at Madison Square Garden as Ewing's finger roll at the buzzer rimmed out.) Two years later, Ewing's line to the media was "See you in Chicago," by which he meant the Knicks would dispatch the Heat in a seventh game at Miami to face the Bulls in the Eastern finals. Naturally, the Heat won. Ewing ended his Knicks career in fitting fashion by guaranteeing a victory in Game 6 of the 2000 Eastern Conference Finals against the Pacers. He missed his final six shots in a 93-80 defeat.
