I didn’t even realize you were naked sis.” Steph had been so focused on what was going on in the hot tub that in her dark bedroom she didn’t see her naked little sister. She started moaning and “ahhing” as she started trembling. I was giving her an orgasm and she was in heaven. She started shaking hard and her hips were moving up and down in a rapid motion before she came to a sudden stop, giving out a loud sigh, obviously recovering from her orgasm. She laid there for a minute trying to catch her breath while she gently pushed me away. She started buttoning up her pajama top, telling me that was enough for tonight and that I needed to get back to studying. I left her room and went straight to the bathroom. My shorts were down by my ankles the second I walked in. Not bothering to close the door, my cock was out and I was stroking hard and shooting my cum into the shower stall in what felt like 30 seconds flat.