The Mishapocalypse was an online flash mob on Tumblr for April Fools this year. Misha Collins is a star on the show Supernatural, and that show, for some reason, is massively popular on Tumblr. Somebody decided that everybody should change their Tumblr avatars to Misha on April 1 to celebrate the man and his work.
Hundreds of bloggers participated in these shenanigans, thus Mishapocalypse.
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