While CERN probably got our vote for best April Fools' Day prank, Tesla certainly wins for managing to convince the most amount of people.
In fact, the prank was so good that it actually sent the company's stocks soaring as shareholders genuinely believed the company had unveiled a new product.
Tesla mysteriously sent out a tweet saying, "Announcing the Model W" on 1 April along with a picture and a link. Of course if you had actually looked at the image, it would have become immediately clear that this was Tesla's April Fools' day prank.
The Model W was in fact a fictional smart watch, presumably as a dig to the rumours that Apple might be competing with Tesla by releasing its own electric car.
Irregardless it turns out that shareholders were so keen to accept the news of a new product that many didn't click on the image or indeed read the press release, resulting in a reportedly staggering addition of $120m to the company's value.