It was a quiet day on the USS Enterprise; no Klingons, no Romulans, no supernovas-threatening-to-destroy-entire-star-systems.
So, naturally, everyone was bored.
Captain Kirk pulled back the rubber band, aimed it expertly, and let it fly.
It hit its target, as it always did. Spock nearly flinched as the rubber band hit the back of his head. It was taking all of his mental control to not turn around and strangle his commanding officer.
Kirk smiled smugly at the tension he could see in Spock's shoulders. If he didn't know better, he would have said the Vulcan was annoyed. Kirk reached into the bag at his side and pulled out another rubber band.
"Keptin! Picking up something on zhe long-range sensorz," Chekov said.
"Confirmed, Captain. Organic, possibly living. Moving at Warp Six," Spock added.
"Is it within viewing range?" Kirk asked, dropping his rubber band (much to Spock's relief).
"...It iz now, sir," Chekov said.
"Put it on the main viewer."
Chekov pressed a couple buttons, and an image of the space behind the Enterprise appeared on screen. Approaching rapidly was a small, grayish entity with a brightly-colored trail behind it. Most confusing, though, was the way the black of space around it changes to dark blue, the stars became undulating points of light, while a hint of an upbeat song reached the crew's ears.
"What is it?" Kirk asked.
"I do not know. However, it does not appear to be hostile," Spock said.
The thing pulled up alongside the Enterprise. Now they could see it: a blocky version of a vaguely feline face, tail and paws, with a rectangular, pink body. The song from before had gotten louder, too.
"The question still stands: What is it?" Kirk asked again.
"Now that I can see it more clearly, I believe it resembles a 21st- century image known as 'nyan cat'."
"It was an image of a catlike being with a body consisting of a pastry known as a 'pop-tart' and it produced a rainbow trail, and accompanied by the song that is playing now."
Kirk looked at the thing on the viewscreen. "And you think this could be one of them?"
"Logically, it could be an illusion of one."
The nyan cat on the screen suddenly veered towards them. The Enterprise shook for a moment, then the nyan song became much louder and unseen lights made the bridge flash rainbow colors.
"Sickbay to bridge! What the hell's going on?!" McCoy's voice burst in.
"No idea," Kirk said.
The nyan cat on the viewscreen had vanished, but the effect it had on the surrounding stars stayed.
"Spock, what the hell's going on?" Kirk asked.
"...I believe the Enterprise is now the source of the illusion. Mr. Chekov, please put an aft image of the Enterprise on screen."
The viewscreen changed again. Now, streaming from the back of the ship, a rainbow-colored disturbance lit up the space behind them.
"...What. The. Fuck." Kirk said.
"Engineerin' to Bridge!" Scotty's voice was frantic.
"Yes, Mr. Scott?" Kirk hit the reply button.
"There's somethin' strange goin' on down here! Th' warp core- well, it doesn' have antimatter anymore!"
"No- well, what does it have?"
"Light! Visible-spectrum light, but almos' in a physical form!"
"...And a catlike thing?"
"Hang on, lemme check-"
Kirk waited anxiously for Scotty to get back.
"Aye, some pink-an'-gray cat thing, flyin' around in there! What is it?"
"A nyan cat."