The New Orleans Saints lost the 2018 NFC championship game in large part to an officiating error: Los Angeles Rams defensive back Nickell Robey-Coleman interfered with Saints wide receiver Tommylee Lewis during a route, striking the defenseless receiver helmet-to-helmet well before the ball was thrown, and without even attempting to make a play on the ball himself. The NFL official watched it happened and did not call foul on any of the penalties Robey-Coleman committed, for which the NFL apologized postgame.
So of course livid Saints fans took to social media and the power of the Internet to protest against this injustice.