In the social-media age, even the most innocent misstep can have unintended consequences, as one NFL rookie recently found out the hard way.

Keenan Allen is a talented wide receiver from Cal who was selected in the third round of last month's NFL draft by the San Diego Chargers. The Chargers and Oakland Raiders share one of the NFL's fiercest rivalries, which is why a random fashion choice by Allen this weekend stirred up plenty of backlash from San Diego fans.

When Allen made a trip to In-N-Out, he posted a Vine video to document the occasion for his many fans. The problem? He wore a Raiders hat. He's since deleted the video, but this screenshot via the San Diego sports blogLobShots.com lives on: