I originally wanted to lose my virginity with my first girlfriend, but I never expected my younger sister to take it from me... IENF-455

My younger sister was utterly shocked that her favorite older brother had gotten a girlfriend for the first time. She was so jealous of that girlfriend that she secretly used his phone to text her saying, "He cheated on me!" and "He has a girlfriend even though he has me as his sister!" She's completely insane! But just as I was drunk and asleep, my sister suddenly took advantage of me, straddling me and swaying her hips! And it felt incredibly good!