The revision history of that post shows that it is not deleted now, nor has it ever been deleted.
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Happy April Fools' Day!
StackEgg is basically a little game where you have to improve the site, taking it from private beta, to public beta, to graduation, to winning the internet.
Come on, let's go win the internet!
Community Wiki isn't a specific page; it's a status. Posts that have been edited a lot,1 and questions that attract a lot2 of answers, are treated as community-owned and are automatically set to CW. This change allows anybody to edit (bypassing reputation requirements). It also ends reputation changes for the original author, as it's now treated more as ...
You can limit your site-wide searches to CW posts using the string wiki:yes (or wiki:no for the opposite effect) in the standard search bar.
You can find out more about Community Wiki posts in our help center or in the MSO FAQ.