One day, while she was doing her homework... I peeked over her shoulder out of curiosity, and saw my little sister rubbing her pencil against the corner of her desk. At first, I had no idea what she was up to. But then, when I realized that she was getting turned on by the friction, her face gradually took on a dazed expression as she climaxed... Could this be ecstasy? Was my sister experiencing orgasmic bliss right there at her desk?!