My sister practices her oral skills on me to better please her boyfriend

My sister is always trying to improve her skills in bed, and this time she's focusing on her oral technique. She's practicing on me, her stepbrother, to make sure she can please her boyfriend when she's away from home. Watch as she gets down on her knees and takes my cock in her mouth, eager to learn and eager to please. She's a natural, swallowing me deep and loving every moment of it. I can tell she's enjoying herself almost as much as I am. After a few minutes of intense practice, she's ready for the real deal. She takes me deeper into her mouth, gagging a bit but not pulling away. The sight is enough to make me cum, shooting a huge load right into her waiting mouth. She swallows every drop, smiling up at me before standing up. What a good sister she is.