GameStop's business is entertainment, but the company made it clear that those on the clock shouldn't be partaking in the fun and games.

The Grapevine, Texas-based company fired an employee who went planking on the job, as well as the fellow employee who snapped the photo of him doing so between two in-store kiosks.

John Mazzocchi, a four-year GameStop employee, planked in what looked like an empty store in Long Island, New York. He Tweeted two photos of himself: one from behind the register, planking between the back and front counters, and another between two merchandise displays. Along with the photos, he Tweeted, "When I go #planking I go hardcore."

Planking is an online craze—started in Australia and New Zealand—where people post pictures of themselves laying flat as a board on Twitter and Facebook. The stranger/weirder/riskier the place you plank, the more online props you get. (Yes, planking can be dangerous: In May, a 20-year-old Australian died trying to show himself planking off the side of an apartment building roof.)

GameStop is known for aggressively monitoring employees' social media activity, and the company has a clause in its employment contract saying employees can be terminated for what they say online about the company.

Mazzocchi, a "senior game adviser," was fired for misconduct. A letter he posted about being denied unemployment benefits noted: "You were employed in a supervisory position and were expected to follow and uphold the employer's policies. Your intentional act to share your on-duty actions via social networking media shows complete disregard for your employer and it is considered a rise to the level of gross negligence."