The Rarest Spooky Boi in the Universe is a Spooky Boi that hid himself by burying himself under the surface of a distant planet's moon. His encounter only occurs if the player has already met The Spook Collector. The player will find two Government astronauts digging him up, and will then have a choice to help the astronauts, the Spook Collector, or the Rarest Spooky Boi in the universe. If they help the astronauts, the Rarest Spooky Boi in the Universe will be taken to an unknown location. If they help the Spook Collector, the Rarest Spooky Boi in the Universe will be taken to Spook Plane 7. If they help the Rarest Spooky Boi in the Universe, the player will receive Spook Coins, two Boneblade knives, and a Skullbuster Rifle. He then leaves to go find a new hiding spot.
The origins of the Rarest Spooky Boi in the Universe are unknown, but he is apparently a one-of-a-kind Spooky Boi, and because of this, he was used for power and leverage over the other Spooky Bois by the rulers of Spook Plane 7. Because of this, he left Spook Plane 7 and hid in the mortal plane of the 3rd Dimension, specifically in the True Timeline. He was hidden for several billion years.
Sometime after the Trans Galactic War and the major conflicts following it, a Military ship beyond Government space picked up a signal from a moon of a desolated planet. Two Government astronauts were sent to investigate, and began to dig him up. That is when the player finds him, and when the Spook Collector arrives. If the player chooses to help the Rarest Spooky Boi in the Universe, they must first distract the astronauts and the Spook Collector, and then help get him a safe distance away from them. There, he gives the player their reward, and then summons a toilet, gets on it, and flies away, searching for a new planet to hide on.
The Rarest Spooky Boi in the Universe resembles a human skeleton wearing an orange retro sci-fi space suit with a white helmet.
"Hey! I'll make you a deal! Get me out of here and away from these other bozos and you'll be rewarded!"
-The Rarest Spooky Boi in the Universe's offer to the player