Big Penguin Race
From the Super Mario Wiki
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Inside the cottage from the first mission, Slip Slidin' Away, is the Big Penguin. When approached, he claims to be the world-champion sledder and challenges the player to a race to the end of the slide. If the player accepts, he immediately turns around and starts to belly slide down, starting the race. If the player takes any kind of shortcut, which includes both skipping part of the course by jumping down and taking the hidden path inside the wall, the Big Penguin tells them that they cheated, disqualifying them from the race. Once the player wins the race legitimately, the Big Penguin congratulates them for breaking his record and gives them a Power Star as a reward.
After the player collects all 120 Power Stars in Super Mario 64 or all 150 Power Stars in Super Mario 64 DS, they can go back to the Big Penguin to find that he has become massive and more difficult to beat due to being "out of shape." There is no reward for winning the race again except for further praise.
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