Status page is not responding either: https://status.github.com/
Seemed to work for me, although it took a while to load and said "All systems operational" edit: Now says "19:32 Eastern Standard TimeWe're investigating connectivity problems on github.com." edit2: "19:47 Eastern Standard TimeWe're investigating a significant network disruption affecting all github.com services."
https://www.dropbox.com/s/ap1nqogmqza2e12/Screenshot%202016-...
And:
cd /[mason@IT-PC-MACPRO ~]$ cd Code/rollerball
[mason@IT-PC-MACPRO rollerball (master)]$ git pull
remote: Internal Server Error.
remote:
fatal: unable to access 'https://masonmark@github.com/RobertReidInc/rollerball.git/': The requested URL returned error: 500
[mason@IT-PC-MACPRO rollerball (master)]$