Sure. The two most popular examples are the C Plus Equality repo and the Operation Disrespectful Nod repo, which were a satirical programming language and a Gamergate resource list for contacting advertisers, respectively.
http://tech.slashdot.org/story/13/12/14/1618239/github-takes...
https://pipedot.org/story/2014-10-04/github-staff-jake-boxer...