Cosmas-the-Explorer 
Explorer in Training
Rarity is actually extremely good at pranks, if she ever feels up to the task. Almost to the point of being psychologically terrifying. If you decided to do a prank with by making her hair green, she'll repay you with a prank that will convince that you're infected with a life threatening disease for a few days. Those do prank her, will learn their lesson when she's through with them