I played a prank on my cute little sister's favorite costume pajamas and made her perky ass completely visible! She didn't know that, but when she put on the pajamas, she realized that her ass was completely visible and puffed out her cheeks! I was excited to see her walk around the room hiding her ass while feeling embarrassed! I got a full erection when she said, "It was you who played a prank on me, big brother! You idiot!"