You are watching your sister in bed... rubbing... her panties... Fucking HOT. Your cock is jumping at all this. You try to be quiet as you watch, not wanting to ruin it. But she senses you and quickly covers her face with her pillow, totally embarrassed. She says to GET OUT of her room NOW. But you aren't moving. This show is just too good to be true, too good to miss out on for sure. So you tell her that you're going to rat on her to Mom and Dad. And that gets her attention. She thinks she may just dissolve entirely if her parents knew she was doing this... she's embarrassed enough as it is to have YOU know. Okay, she's saying she'll do ANYTHING for you to not tell on her. And here we are, the perfect position. You tell her to finish what she started, keep rubbing herself... but without the panties. At first, she's not interested, but she can't help herself as she gets into it and cums hard!