In 1953, people began calling into the police station in Atlanta, Georgia to report UFO sightings. All it took to get everyone seeing flying saucers was three guys, a dead monkey, and a few basic household ingredients.
So it was a balmy night in July in 1953 and three guys (two barbers and a butcher) found themselves in possession of a dead rhesus monkey. What were they to do? They could have carefully skinned and stuffed it. They could have held a small ceremony and buried it. They could even have roasted it. Instead, they decided to make the whole town of Atlanta lose its mind.
A trip to a drugstore got them green food coloring and hair remover. Presumably the barbers went to work with the hair remover while the butcher removed the monkey's tail. After a dip in the green food coloring, they took the corpse on a road trip. At a certain deserted section of the highway, they used a torch to burn some scorch marks into the pavement, and set the mutilated monkey down near the marks. When a highway patrol car came along, they said that they had plowed through a gang of creatures, hit one with their car, and watched the rest pile into a flying saucer that rose up into the sky.
Then all hell broke loose. The patrolman filed a report that included the claims the trio had made. The press called. The Air Force called. Hundreds of citizens called, saying they'd seen colored objects in the sky. A local veterinarian said the corpse looked "out of this world" and the calls increased. Within hours, Atlanta was being invaded by aliens.
In another couple of hours, the panic died down. A local anatomy professor was pressed into service and immediately identified the corpse as a hairless monkey. The word got out, and the three, perhaps a little flustered by the success of the prank, admitted to what they'd done. It seems that "making people believe in UFOs" isn't a crime (which is a shame, because what a trial that would be), and so one of the barbers was fined $40 for obstructing a highway.