TL;DR: I created a rumor that our company was being bought out, which by sheer coincidence had implications at the CEO level.

Back in the mid-90s, the day before April Fools Day, I wrote a fake Wall Street Journal article about Toshiba buying up our company's stock, i.e. a hostile takeover. As a clue that it was fake, I made the Toshiba spokesman's name Igata Takashawa. I scribbled an illegible name on a printed copy and left it on a random manager's desk.

Within 2 hours my dept suddenly had an emergency all-hands mandatory meeting. The room was packed, and projected on the wall was my article. It was utter pandemonium in there, everyone talking at once. Because of April Fool's it was also "funny hat day". A few people had funny hats, but our manager had gone all out and was dressed like a pirate - black pants, big white shirt, red bandana and a giant gold plastic earring. He was British and strongly resembled actor Bob Hoskins - bulldog-like build, blustery attitude. When I walked in he was standing on a chair waving his arms trying to get everybody to shut up.

It seemed upper management was very disturbed by the article, and wanted whoever created it to come forward. They promised no recriminations (yeah right) and only wanted to know the reason for it. I kept my mouth shut.

A friend of mine, who worked near a bunch of managers and overheard their conversations, said their tone was like, "Why Toshiba?" and "Why now?" - as if the story might have a grain of truth.

It came out months later that by sheer coincidence our company had been working jointly with Hitachi on a top secret military project - a portable, battlefield ultrasound machine to detect plastic sharpnel, which didn't show up on x-rays. The engineers called it "the tricorder" because it resembled the one Spock used to carry. The boys at the top wondered if the article was a subtle message that the secret had leaked out, which could affect their ability to get future government contracts.

Anyway, I left that job within a few months but my friend stayed for 7 or 8 years, and he said every April Fools Day the "Toshiba incident" still came up in conversation.