your step-sister Red August finds you in your parents room, on their bed jerking off! She also found her panties hidden in your room too! She giggles at busting you jerking it, you perv... but don't stop. she wants to see if you're doing it right ... you're not doing it right so she gives you specific instructions to follow along, how to stroke it, cupping your balls, hand motions etc. faster and faster until you explode cum all over mum&step-dad's bed! she threatens to tell your parents cuz that's what big mean sisters do!