Extraterrestrial Signal
The Wow! Signal, as it was named, was never heard again, which makes people think that it was extraterrestrial. Others theorize that it was a comet that the telescope was picking up, or maybe a glitch in the telescope. There's never been a concrete answer for this sound.
The Freemasons Yearly Meeting
The Freemason group called Robert Burns Masonic Lodge holds a yearly meeting at the Malheur Cave in Oregan. The 3,000-foot cave was once used by Native Americans. Of course, this event on its own leads to many conspiracy theories.