Late last year, Slate compiled a visual guide to what they called "the year of outrage." In the accompanying article(s) they did concede that a few of the things that outraged us last year were deserving of it. They also pointed out that "it’s fascinating to look at how our collective responses skipped from the serious to the picayune without much modulation in pitch."
So what should we be outraged by? Slate's guide offered reader input, so you can check each outrage in hindsight and see what the collective thought. (ex: John Travolta's mispronunciation of Idina Menzel's name was voted overblown by 1195 to 107, while the non-indictment of the NYPD officer who killed Eric Garner was declared to be truly outrageous by a 1530 to 113 vote.) But if Slate continues to follow our Twitter and Facebook outrage in 2015, I can already tell you what will be legitimately labeled outrageous.
When proponents of a religion massacre human beings in retaliation for drawing a picture.