From the Super Mario Wiki
Bowser: Accused! is a quest in Mario Party Advance. It is initiated when the player enters the Bowser Mansion, where Shroomlock is accusing Bowser and Koopa Kid of stealing a painting from the local museum. Bowser notices the player's arrival and asks them if they believe that he is guilty as well: they can either leave immediately, to Bowser's confusion and Shroomlock's disappointment, or they can say that they believe Shroomlock, immediately starting the quest. The player is given the task of finding a flaw in one of Bowser's stories, and is then prompted to ask him about his alibi, the painting, or the mansion. Asking about his alibi leads Bowser to claim that he was in his mansion while the theft took place, asking about the painting has him comment that he has never seen the painting before, and asking about the mansion leads him to a comment about the mansion's clock being too small to hide the stolen painting; however, if Bowser had never seen the painting, he could not say that it is too big too hide behind the clock, which means that he lied in the mansion's story. When asked about this, Bowser admits to stealing the painting, and sends Koopa Kid to pick it up behind the mansion. He then challenges the player to a Bowser minigame, Mush Rush. If the player loses, Bowser faces no repercussions for stealing the painting, forcing the player to restart the quest, while beating Bowser makes him admit defeat and give the player the Lip Sync Gaddget.
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