A kindergarten teacher was teaching her class the alphabet. She asked the class, "What starts with the letter 'A?'"
She sees Little Johnny in the back raising his hand. Knowing that Johnny is very foul-mouthed, she calls on a little girl in the front row.
The girl replies, "Apple."
"Very good," said the teacher. "Now, who knows a word that starts with the letter 'B?'"
Again, Little Johnny is waving his hand in the air wildly. And again, she does not call on him, but instead calls on a boy in the back of the room.
"Baby," he says.
"Very good."

She continues to go through the alphabet in this manner. All the while, Little Johnny is begging to be called on. Each time, becoming increasingly insistant. Finally, when she got to the letter 'R,' only Little Johnny had his hand up. Sighing, the teacher said, "All right Johnny, what starts with 'R?'" She braced herself for the worst.
To her surprise, Johnny said "Rat."
"Rat?" the teacher responded. "Why, yes, Johnny. Very good."
"Yeah, rat. A big f---ing rat with a dick this big!"