When his older brother scooped his own eyes out, Button Mash didn't feel guilty.  It wasn't his fault.  His older brother was... not right in the head, so it was easy to pull tricks on him.  Button was only doing what few younger brothers get to do.  Although he loved his brother, and protected (tried) to protect him from bullies, it was fun to play a few tricks on him every now and again.

The two brothers were lying flat in the grass outside of their house, tossing tennis balls at each other when Roller Bash asked a dumb question.  "Hey Button.  What are those things up in the sky?  If I stay still I can see them moving around."

Button knew about eye floaters.  Everypony knew about eye floaters, but his brother didn't.  Button immediately saw this as an oppurtunity.

"Oh my Celestia, you see them too?  I thought I was the only one!"  From then on it was fairly easy.  One Roller got "good" at seeing ghosts in the sky, Button taught him to sit very still, and practice so that he could see ghosts in the walls, or drifting passed the window.

Button would point one out, and Roller was convinced that he could see it too.  Button had given his brother plenty of time to catch on, hadn't he?

But after a couple of weeks, Roller freaked out and had to be rushed to the hospital when he maimed himself.  Button felt a little guilty at first, but then they let him talk to Roller for a while.  

"Why did you pull your eyes out, idiot?"  Button asked.

Roller turned his head, as if he could see through the bandages.  Button felt a chill run through him.  "I didn't," Roller whispered.  "Ghosts don't like to be seen.  They can't stand it.  And Button,"  He reached out to grasp Button's leg.  "Be careful.  They know that you can see them too."