It was part of a promotional stunt for a movie being made by several local filmmakers about a historic event known to UFO buffs as "The Maury Island Incident".
The movie is based on a UFO encounter that happened off Maury Island in June of 1947. It's often overlooked because it happened just two days before Ken Arnold's famous Mount Rainier sighting and two weeks before the infamous alien crash near Roswell New Mexico.
"It about a man who decides to tell the world a story and they don't believe him and what happens to him which is horrible," said Steve Edmiston, the film's screenwriter and co-producer. "It's also about what happens to the people who look into the story which is tragic"
Two air force investigators who were piloting a B-25 allegedly carrying evidence on the encounter died when their plane went down near Kelso on August 1, 1947.
It's considered by many experts to be the first "Men in Black" encounter. UFO lore states that men in black were known to mysteriously appear after people encountered aliens.
Having a UFO block party on April Fool's was a mere coincident said one of the promoters with a smile. People dressed up as men in black and famous and not so famous aliens. A flash mob broke out in dance to the song Secret Agent Man.
The film's executive producer John White built a flying saucer that landed on a 1947 Buick Roadster which is considered to be the original man in black car.
Filming for the short film will begin in June. The script is based on FBI documents that were declassified 50 years after Harold Dahl first reported seeing flying discs over Maury Island in Puget Sound.