I pulled my boxers off and positioned myself behind mom. Her body slightly trembled in anticipation.I wrapped my hand around the base of my erection a...d slowly pushed the tip into mom's wet vagina. She softly moaned. I slowly pushed my entire length inside and stopped. I closed my eyes and enjoyed the incredible felling of having mom's wet vagina wrapped around my erection. It has been such a long time since mom and I have had sex and I wanted to enjoy the moment.I opened my eyes and saw mom's. He started touching her already wet pussy. He inserted two fingers inside."Oh Sam, that feels so good. I forgot how good you felt." Kristin moaned out. Sam went faster and faster until he felt Kristin cum on his fingers."Really, you're going to make me watch this? Is this more punishment big brother?" Liz asked. Liz was watching the whole thing, and it made her hornier than ever before. It's was hot watching some one else get touched."Yep. This is only the beginning of what you are about to see. "I replied, "I'm sorry Mom. I wasn't sure how far to go. After letting me seeing you in action with dad I thought you'd want to hear something hot."Mom said, "I guess we never discussed any limits."I came back with, "You should have stopped me Mom. I could have told you another story." No, baby it's OK. In some way I'm glad you feel comfortable enough with me to share such details. I doubt your friends have a close enough relationship with their parents to have these kind of talks."I replied,. .I don't want to get caught."His eyes were closed, and a soft smile played at the corners of his mouth as the last of the incident played through his mind. He was so caught up in the memory that he failed to hear the sound of his sister's footsteps as she entered the living room."What are you so deep in thought about?" he heard Cynthia ask.Dragging himself back to the present, Sean turned and saw his sister padding across the living room toward him. She had a big, white towel wrapped around her.