At 10:23 UTC on April 1, 2015, stackoverflow.com enabled an April Fools' prank called StackEgg.1 It was a simple Tamagotchi-like game that appeared in the upper-right corner of the company's website. Though it had been tested, we did not account for the additional network activity it would generate. By 13:14 UTC the activity had grown to the point of overloading the company's load balancers, making the site unusable. All of the company's Web properties were affected. The prank had, essentially, created a self-inflicted denial-of-service attack.
The engineers involved in the prank didn't panic. They went to a control panel and disabled the feature. Network activity returned to normal, and the site was operating again by 13:47 UTC. The problem was diagnosed, fixed, and new code was pushed into production by 14:56 UTC. The prank was saved!