"Letter's On Fruit" joke

A teacher comes into the class room and there is a red apple with the letter "T" on it setting on her desk. She asks: "My what a pretty apple. Who brought this to me?"
Little girl in the front row replies: "I did teacher."
The teacher asks: "What does the letter "T" stand for?"
"Teacher", she replies.
The next day there is a great big red apple, with the letters "TT" on it.
"My what a big beautiful apple who brought this to me?"
Little boy in the back row says: "I did."
"Why thank you, but what do the letters "TT" stand for?"
"To Teacher", he replies.
A couple of days later there is a huge watermelon on her desk with the letters "FUCK" on it.
She asks: "Who brought this watermelon in?"
A little black boy in the center of the class replies: "Why i did teacher".
"Why thank you very much. We'll have this at recess, but do you know what the letters stand for?", she asks in a upset tone.
"Yes ma'am. From Us Colored Kids..."