Quoted from Jokebudda: Two priests were going to Hawaii on vacation and decided that they would make this a real vacation by not wearing anything that would identify them as clergy. As soon as the plane landed, they headed for a store and bought some really outrageous shorts and shirts, sandals, sunglasses, etc. The next morning, they went to the beach, dressed in their "tourist" garb and were sitting on beach chairs, enjoying a drink, the sunshine and the scenery. Presently, a "drop dead gorgeous" blonde in a tiny bikini came walking straight toward them. They couldn't help but stare. As she passed them she turned, smiled, and said: "Good morning father, good morning father." Nodding and addressing each of them individually. They were both stunned; how in the world were they recognized as priests? They went back to the store, bought even more outrageous outfits and again they settled on the beach in their chairs to enjoy the sunshine, etc.
After a while, the same gorgeous blonde, wearing a string bikini this time, came walking toward them again. (They were glad they had sunglasses, because their eyes were about to pop out of their heads).
Again, she approached them and greeted them individually: "good morning father", "good morning father" and started to walk away. One of the priests couldn't stand it and said, "just a minute young lady. Yes, we are priests, and proud of it, but I have to know, how in the world did YOU know?"
"Oh father, don't you recognize me? I'm Sister Kathryn!"