We've mentioned before that Oscar the Grouch used to be orange; Jim Henson decided to make him green before the second season of Sesame Street. Oscar explained the color change by saying he'd gone on vacation to the very damp Swamp Mushy Muddy, and he turned green overnight.
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You guys can probably do better than that. We'll award three mental_floss t-shirts to the people who provide the most amazing Sesame Street/Muppet Show/Fraggle Rock facts. Or Muppet Babies. Did Nanny have a full name? That's the kind of thing that might win you a shirt.

We'll announce the winners next week!