I walked in on my step sis after she stepped out of the shower and she was naked, drying off. I went into my room to jerk off and she walked right on in to approach me about what happened. Embarrassed, I told her to leave but she wouldn't. She rather lie next to me and flirted with me. I told her my girlfriend was coming back home soon but she didn't care. We made it quick and she didn't want me to cum in her but I busted before I could even react and pull out. She was mad but the door opened and she hid in my closet, naked and full of my cum as my girlfriend was walking through the door.