The setting: backroom of a grocery store; dingy, drab. Surveillance and sporadic managerial presence precludes elaborate set-ups. A radio is the sole prop.
The victim: a co-worker of many years. Intelligent but gullible, knowing enough about the Large Hadron Collider (LHC) to often express fear that it will create a black hole, but not enough to know its schedule.
The occasion: my last day of employment at the store (after eight years).
THE PRANK: Sort of a copy of the famous War of the Worlds radio broadcast. I took a few songs that the local classic rock radio station plays, a station identification I recorded from an online stream, and an Emergency Alert System tone, and (what I thought would be) an official-sounding message created by a reasonably human-like voice synthesizer. I then arranged them all in the right order and burned a CD. At work, I cut short my break so as to get to the backroom first. I turned the CD on. When the co-worker arrived a few minutes later, he had no idea that he was hearing a CD instead of the audio.
A few minutes later, as we were listening to 'Heat of the Moment' by Asia, the EAS alert tone began. He shushed us all and told us to listen. Then the tone ended and the message began: "This is an activation of the Emergency Alert System. Within the last 35 minutes contact has been lost with the area surrounding the Large Hadron Collider in Geneva, Switzerland. The likeliest explanation is that today's initial testing of the supercollider has unexpectedly resulted in a worst case scenario, the creation of a micro black hole. Due to the catastrophic nature of this occurrence, the President has ordered a curfew..." You can listen to the audio I used for this (242 kb ogg).
Initially dazed, my coworker quickly realized what (he thought) was happening. His eyes bulged, his face blanched. He started moving around without any objective other than to stifle the panic. He started to run.
And here is where planning coincided with fortuity to create a perfect vortex of malicious prankster goodness.
He got a series of texts at the very moment this 'warning' was playing on our stereo. As he stumbled around, terrified, he was fumbling in his pocket for his phone. If his inability to get his phone from his pocket to his hand was any indication, his mind was not working well. And as my two coworkers and I stood watching (in on the prank, they pretended not to understand the import of the message), the victim yelled, "DO YOU KNOW WHAT THIS MEANS? WE'RE FUCKING DEAD!"
I couldn't contain my laughter another second. I burst out laughing, called him a moron, and explained what happened. He was a bit miffed, understandably, but he appreciated the joke and congratulated me. But for the rest of the night I swear he was jittery and short of breath. He even said I took years off his life!
Well done, me!