Sorry for the long joke.....
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I saw a girl walking down the street that I fucked years ago, so I ran up behind her, covered her eyes and whispered, "Guess who... I took your virginity..."
She said, "Dad?"
"Dad?" I replied, staggering back in disgust. "You lost your virginity to your Dad?"
She turned round and said, "Oh... It's you... I told you that you were my first because I was ashamed of what happened with my..."
"I don't want to hear it," I interrupted. "Fuck you, and your Dad."
As I walked off, I turned round and shouted, "Tell him Uncle Tony won't be coming round this Christmas."