Rarity invites Twilight over her house to hang out and show her a new outfit she has. When Twilight arrived, she was greeted by Rarity holding a straitjacket in front of her. Twilight was intrigued, she never worn a straitjacket before and thought it would be fun so Rarity went ahead and tied up Twilight. After she trapped Twilight in the straitjacket, Rarity gave her a ballgag to wear and had a lotta things planned with her. I don’t think Rarity will ever let Twilight out any time soon.