Oh, I went to check what badge that was and it's for 'Great Share': "This badge is granted for sharing a link that was clicked by 1000 outside visitors. Wow! You've promoted an interesting discussion to a huge new audience, and helped us grow our community in a big way!" That's seriously impressive...
I have noticed there are some badges no one has ever gotten: Promotor, Campaigner, Champion, and First Reply by Email. There isn't an option via email for the last one, so that should be removed, lol. Unless they're working on a way for that to happen in the near future?