Thoughtco describes the origin and spread of the McDonalds human meat story.
https://www.thoughtco.com/human-meat-found-in-mcdonalds-factory-3298794
The McDonalds human meat story appears verbatim on several sites. The earliest was Huzler's on 8 February 2014. Huzler's is a satire site like the Onion.
http://web.archive.org/web/20140327054929/http://huzlers.com/mcdonalds-exposed-for-using-human-meat/
McDonalds Exposed For Using Human Meat! (Must Watch Video)
Other examples of Huzler articles here:
http://web.archive.org/web/20140410121146/http://huzlers.com/
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