The Nuns

Three nuns passed every day through a street that led them from Church to a Reformatory. They noticed a parrot that stood at the entrance of a big residential house. 

Every time they passed in front of that house, the bird would pronounce three sequential colors. One day, they heard, "yellow, blue, black." One of the nuns noticed that those colors perfectly matched the colors of their underwear. She mentioned her discovery to the other two nuns, but both were reluctant to believe that could be possible. 

The next day, they all wore black underwear and passed in front of the house, and very precisely the parrot spoke, "black, black, black." Hearing that, the three nuns were astonished! One of the nuns spoke up, "Girls, tomorrow we are going to trick that bird." Saying that, she recommended that the next day, none of them should be wearing any underwear under their vestments. 

Respecting their agreement, the next day they wore no underwear, and proceeded to pass in front of the parrot's house. They peeked at the bird. At first the parrot looked a bit puzzled, he swung back and forth on the cane he was perched on. Then, after a while, the Parrot said, "Straight, Straight, Curly!"