They lost. They lost a bet against Applejack and Rainbow Dash of all ponies. What ended up turning into a simple guessing game as to how many emergency stashes Pinkie had around Ponyville turned into an all-out competition between them. (Mostly because of Rainbow Dash.) The prize of the bet: The losing couple had to be the winner’s servants for a week. Unfortunately for Rarity and Twilight, they were just slightly off from their competitor’s guesses, and thus, they became the prize.
 
But it didn’t just end there. To make it much worse, their first request: For both of them to wear a Prench Maid uniform for the entire duration of the time agreed upon. And out of Rarity’s many designs, they made sure it was the skimpiest of them all. Not having any choice, they changed into their uniforms and stepped onto the dressing platform for their temporary masters to see how they looked. Twilight was less than comfortable in her attire, but at least for Rarity, she can’t complain about getting to see her marefriend in a maid outfit for the week.