Burt the Bashful
From the Super Mario Wiki
Burt the Bashful is the first mid-boss seen in Super Mario World 2: Yoshi's Island; he is found in World 1-4, Burt the Bashful's Fort. At the end of the fort, Yellow Yoshi encounters a normal Burt, which Kamek grows to a massive size, turning it into Burt the Bashful. To defeat him, Yellow Yoshi must hit him with eggs six times; with each hit, Burt's pants continue to fall off. When he is defeated, his pants entirely fall off and, ashamed, he turns red, eventually imploding. While Burt does not appear in Yoshi's Island DS, the mid-bosses of World 1, the Burt Brothers, are based on him. Burt the Bashful later appears in Yoshi's Woolly World as the boss of World 1 in World 1-8, Burt the Bashful's Castle.
In volume 14 of the Super Mario-Kun, the volume based on Super Mario World 2: Yoshi's Island, Burt the Bashful is the first boss Mario, Luigi, and Yoshi encounter. He bounces around, smashing Mario in the process. Yoshi also attacks and ends up failing. An Egg-Plant assists them, but the Yoshi Eggs simply bounce off Burt. Finally, Mario, Luigi, and Yoshi grab and pull down Burt's pants, revealing his genitals. Ashamed, he shrinks and starts flying off as a deflated balloon, causing havoc to Mario and Luigi.
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