Amateur step-sister discovers step-brother's solo pleasure session

My step sister was always a whore from the first day we met. Her small tits and shaved pussy were always wet and ready for a good fuck. One day, I caught her wanking off her stepsister and couldn\'t resist the urge to join in. The sight of her tight pussy being fingered and jerked off was too much to handle, and I ended up cumming all over her.