A plan to 'Storm Area 51' in search of aliens on September 20th started out on Facebook as "kind of a joke" which spiraled out of control, according to the guy who created the event.

"I posted it on like June 27th and it was kind of a joke," Matty Roberts told Nevada's KLAS-TV. "And then it waited for like three days and like 40 people, and then it just completely took off, out of nowhere. It’s pretty wild."

Now, over 1.7 million people have signed up for the Facebook event, with another 1.3 million people having expressed interest in the event.

Roberts, who had initially communicated with NPR anonymously via Facebook messenger, says he was worried that the FBI would show up at his house.

Roberts says he came up with the idea after Joe Rogan interviewed Area 51 whistleblower Bob Lazar and filmmaker Jeremy Corbell. During the interview, Lazar claims to have been involved in all types of alien matters while working at a branch of Area 51 known as "S4," where he was tasked with reverse-engineering the propulsion system on one of nine flying saucers kept on the base.

Lazar said this of the inside of a UFO: "It’s a very ominous feeling because everything is one color. It’s like a dark pewter color. There are no right angles anywhere. It’s as if somebody took a model and fashioned it out of wax and then heated it just for a short time so everything melted. Everything looks like it’s fused together. Everything has a radius, a curvature where two items meet. It’s a really weird looking thing. There was almost nothing, other than a small foldable hatchway, that looked recognizable. Everything was really unworldly."

Needless to say, the "Storm Area 51" event has attracted a ton of attention.

The event — a tongue-in-cheek attempt to find aliens hidden by the government — has taken on a life of its own in the internet zeitgeist, receiving nods from celebrities and brands while also turning into its own meme on the short-form video app TikTok. Celebrity chef Guy Fieri jokingly offered to cater the event with radioactive ribs. Bud Light created an Area 51-themed beer can. And MoonPie naturally got in on the fun. -NBC News

Rapper Lil Nas X even came out with a special alien-themed video for his hit, "Old Town Road."

Roberts says that while he doubts the group will form an actual army to make a run at Area 51 this September, he's met "some pretty great people" along the way who are planning a safer event, per CNN.

The Air Force, meanwhile, has issued a warning that is not a joke - warning that "any attempt to illegally access the area is highly discouraged."