At the Christmas party

Last weekend at my wife's Xmas party, one of the girls in her office, Cindy, had been VERY friendly to me; my wife told me when Cindy went to the loo that Cindy had told her that she intended to dress slutty and get fucked that night, and by the way is your husband going to be there? My wife laughed, and told me "go for it if you want." (We used to swing until we moved about 2 years ago.)
About 10 PM, after we had all eaten and had enough to drink we were all happy, relaxed, and friendly, Cindy comes over again to where my wife and I were sitting; she leans over to me and says in my ear, "I need to tell you a secret." I say. "I'm listening." She says "No, over here," motioning me to follow her. I look over at my wife, who winks, and get up following her through the crowd across the room. She tugs on my sleeve (she's about 5' tall and 95 pounds, and I'm 6' 2" and 210) and asks me to lean over so she can whisper in my ear: "You're the best looking man at this party, and if your wife ever gets through with you, can I have you?" I smiled at her and said "Why wait? You can have me right now." She grinned and said "How about your wife? I don't want to cause her any trouble." I told her "Go ask her and I'll meet you outside." I walked away down the hall." In a minute I went out the front door and down the drive about 40 feet, into the dark but still in sight; she came out all smiles, came to me and said "I can't believe it! She said go ahead!" I took Cindy's hand and led her across the yard to the unlocked boathouse. Once inside I turned her away from me, toward the lake, put my arms around her, pressing my now raging hard 10" dick against her tiny but perfect ass and began to rub her tits. As I kissed and nibbled on her neck & shoulders she began to rub her ass against me, moved her arm up to touch my neck, and her head around to kiss me. Her nipples began to get hard and long under my fingers, and she reached around to rub my dick. She began to groan, then turned around quickly, unzipped me, and let the monster out, dropping to her knees and swallowing me all the way. She sucked and bobbed her head like a mad woman until I thought I would explode. I pulled her up to me, kissed her hard, tounged her deep, and pulled her long dress up to reach her panties; I was surprised to find her bare assed! She whispered "I knew I was going to fuck someone tonight so why wear my usual thong?" She grabbed my dick, groaning "Fuck that's the biggest dick I've ever had" and slipped it in her wet & dripping cunt. I fucked her slow and deep, listening to her groaning and moaning getting slowly louder. She said "Let me lay down" and pulling her dress over her head was naked in 3 seconds; she lay down on a stack of cotton tarps ass up, and I was on her and in her in a flash. She pushed back hard at every thrust, and I went from deep and slow to deep and fast, holding on to her perfect little ass and her short black hair. As she moaned and bucked she began to talk dirty: "Fuck me, fuck me, fuck me, harder, faster, make me your whore." She came, screaming, and I knew anyone within 100 feet would hear us but I didn't care; I kept on fucking her, faster and harder; she came again, screaming again; and I began to come myself, great buckets of hot come, filling her up, running down her thighs and ass. She collapsed onto the pile of tarps. I lay beside her for a few moments and she said "God that was the fuck of the century."
Cindy has now moved in with us...but that's another story.