A surprise

Suddenly the closet door opens and Amy emerges.

"Amy, what are you doing here?" I said.

"Watching my big sister suck your dick." she answer seductivly. She goes up to the bed and start kissing her sister, while I watched them both stunned. "I have wanted to introduce you to my sister for a while, she has been sooo jealous of me." Amy continued while taking off her clothes.

My dick instantly returned to it's state of erection.

"Fuck your girlfriend now" Mary whispered. "I want to watch you."