Vacationing in Hawaii, two priests decide to wear casual clothes so they won't be identified as clergy. They buy Hawaiian shirts and sandals, and soon head for the beach.
They notice a gorgeous blond in a tiny bikini. "Good afternoon, Fathers" she says as she strolls by.
The men are stunned. How does she know they are clergy? Later that day, they buy even wilder attire consisting of surfer shorts, tie dyed T-shirts, and dark glasses.
The next day, they return to the beach. The same fabulous blond, now wearing a string bikini, passes by, nods politely at them and says, "Good morning Fathers."
"Just a minute young lady.", says one of the priests. "We are priests and proud of it, but how in the world did you know?"
The blonde replies, "Don't you recognize me? I'm sister Katherine from the convent."