Due to a consistent feeling of boredom for the past few months, Twilight has been developing a potion designed to reconfigure the body of the user.

Rainbow Dash happens to learn of this on the day she's looking for volunteers, and offers herself as a guinea pig to test the effects of the potion.

Twilight then makes sure it worked completely.

Massive thanks to MrSp33dy for proofreading, editing, and generally being an awesome human being...

Or at least, a being that somewhat amounts to the approximation of a human, you can never quite know with the Internet.