My sister came to my house as a tutor and she's so erotic that I can't concentrate on studying! When my parents aren't looking, she lets me touch her boobs, plays with my dick all the time while I'm studying, and makes me have sex with her as a reward for solving problems... Anyway, my academic performance is declining and I'm in a pinch! But sex with my sister feels so good!! She gives me a three-point blowjob that doesn't leave both nipples unattended, and she gives me an erotic grinding cowgirl position where she swings her hips back and forth, and then she puts her whole weight on me and presses me from above to squeeze out my semen! Ahhhhh, it's the best!! At this point, I've given up on going to college! I want to spend my life doing erotic things with my sister forever!!