So here's a more serious discussion of what 'GitHub' is, and why Microsoft's acquisition of it is so important: China can't block GitHub's pages about the Tiananmen Square massacre.
China has their Great Firewall to block 'bad' content. It can't block individual GitHub pages because GitHub forces the use of SSL/TLS, which encrypts the connection, so the Firewall can't see which pages are being accessed.
The only option would be to block the entire site, all access to GitHub.com, but China can't do that either, because so much source code is hosted on GitHub -- source code their industry needs in order to build products.
There are few websites on the Internet so powerful as to be above blocking by the Chinese government, and GitHub is one of them.
When Microsoft buys GitHub, however, China will now have leverage, threatening other Microsoft interests in China in order to pressure Microsoft into censoring some GitHub pages.
Microsoft has the #3 largest market cap in the world (after Apple and Google), so you'd think they are all powerful. It means they opposite, that they are tied to so many things, their interests so broad, that they can be hurt. It's narrow, focused companies that are powerful.
