This role-play is performed by adults. One day... I thought she was having sex with me while I was doing my homework, so I looked in and saw my sister rubbing her clit on the corner of the desk... At first, I had no idea if she was having sex with me... I thought that if my clit was itchy, I should just scratch it with my hand, but then her face gradually became ecstatic and I started cumming... Is this some kind of ecstasy? Was my sister experiencing orgasmic ecstasy on the corner of her desk? !