A nun gets into a cab and the driver keeps staring at her through the rear view mirror. "You know, Sister," the cab driver says, "I hope you aren't too offended, but I've always had this fantasy of getting a blowjob from a nun."
The nun thinks for a moment and says, "I'm not too offended. I just have two requirements. One, that you be single, and two, that you be Catholic."
"Oh yes, Sister, I am single and Catholic," the cab drive replies, so they pull into an alley and the nun proceeds to satisfy the cab driver orally. After they're done, the cab driver begins laughing.
"What's so funny?" the nun asks. "Ha ha!" the cab driver annnounces, "I fooled you sister. The truth is I'm really married and I'm Jewish!"
"That's okay," the nun replies, "My name is Bob and I'm on my way to a fancy dress party."