Amnesia

Fluttershy ran into Twilight's library and saw Rainbow Dash lying on the floor with books around her, next to a half destroyed bookcase.

"What happened?" Shrieked Twilight when she saw the hole in her roof.
"Err... Flying accident." said Fluttershy

At that moment Rainbow Dash gets up and shakes her head.

"Great one, Fluttershy! Look what you did!" Said Rainbow Dash
"Oh. I'm sorry. I didn't mean to..." Said Fluttershy

Then, Rainbow Dash started lecturing Fluttershy on how she needs to be a better flyer and how it should be 'in her nature' to be a good flyer.

As Rainbow Dash was talking, Fluttershy noticed the bookcase tilting forward a little.

"Umm.. Rainbow Dash?" Fluttershy said quietly.

Rainbow Dash just ignored her and kept talking.

"The... the bookcase. It's moving..."

Still, Rainbow Dash kept ignoring her.
Then, the bookcase came of the wall and started falling straight toward Rainbow Dash. Fluttershy screamed at the last second: "WATCH OUT!"

Fluttershy leaped toward Rainbow Dash and shoved her out of the way.
Then, one moment later, the whole bookcase came crashing down. On top of Fluttershy.

"Twilight! Help me!" Yelled Rainbow Dash as she attempted to lift the bookcase off her friend.

Twilight ran over to the bookcase and helped Rainbow Dash lift it off her.
And underneath was Fluttershy. Out cold.