It is often cited in historical texts and popular culture that people laughed at Christopher Columbus when he said the world was round. In fact the actual reason he was laughed at, was that he had prostate cancer, and was prone to bouts of incontinence.
Columbus was a notorious liar, and it's entirely possible that he never went to sea, much less discovered a continent. Other rubbished claims included claiming he was a woman, that he'd invented a new type of biscuit, but couldn't tell anyone because it was a secret, and that he'd invented a new colour but couldn't remember where he left it.
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