From the Super Mario Wiki
“Yikes!! They're pretty tough!”
Grate Guy is a jester in the game Super Mario RPG: Legend of the Seven Stars. He and his partner, Knife Guy, work for Booster as bodyguards as well as jesters. As Booster flees to Marrymore with Princess Toadstool in tow, Mario is prevented from leaving Booster Tower by the pair of jesters. As such, Mario and company must battle Grate Guy and Knife Guy on the balcony of the tower. Grate Guy wields impressive magic, but he and his partner are eventually defeated.
Later in the game, Grate Guy opens up Grate Guy's Casino. The entrance to the casino is well hidden in the underground of Bean Valley. Only those with a Bright Card, the casino membership card, may enter. Mario can win a membership from Knife Guy. The odds at the casino are terrible however; Mario and other casino members can lose a lot of coins here, much to Grate Guy's satisfaction.
Grate Guy holds no grudges against Mario and will even play the game "Look the Other Way" with the plumber. To play, Mario must guess which way Grate Guy will look, and look the other way. Essentially, the game has 50/50 odds. If Mario wins, he will be usually be rewarded with sub-par prizes such as a Rotten Mush or a Wilt Shroom and a Moldy Mush, although he will occasionally receive rare items like Red Essences and Kerokero Colas. If Mario plays a hundred times, he will be rewarded with the Star Egg, an extremely powerful item.
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