Hawaiian vacation

Two priests were going to Hawaii on vacation. To improve their chances of having a real vacation, they decided not to wear anything that would identify them as clergy.
As soon as the plane landed, they headed for a store and bought some really outrageous shorts, shirts, sandals, sunglasses, etc.

The next morning, they went to the beach, dressed in their "tourist" garb. They were sitting on beach chairs, enjoying their drink, the sunshine and the scenery when a drop dead, gorgeous, blonde in a tiny bikini came walking straight towards them. They couldn't help but stare.

When she passed them, she smiled and said, "Good morning, Father," nodding and addressing each of them individually, then passed on by. They were both stunned. How in the world did she recognize them as priests?
The next day they went back to the store and bought even more outrageous outfits - outfits so loud you could hear them coming before you even saw them. Once again, they settled down on the beach to enjoy the sunshine.

After a while, the same gorgeous blonde came walking toward them.
Again, she approached them and greeted them individually, said "Good morning Father," and walk away.
One of the priests couldn't stand it. "Just a minute young lady," he said. "Yes, we are priests, and proud of it, but I have to know: how in the world did you know we are priests?"

"Father, it's me, Sister Mariam."