Continuation of the Serving Your Sister series. Your big sister isn’t convinced that you actually love her. Maybe you just love the orgasms she lets you have in front of her. But there is something you can do to convince her that you do love her–you can let her bust your balls with her knees. You agree and she stretches her legs. Eventually she starts kneeing you, making you say please and thank you for the ball busting. She starts to get warm and strips down to just her underwear and knee high socks. You’ve done such a good job that she’s convinced you actually do love her…and now she knows she loves busting your balls too!