School days

One day Johnny is in class, and his teacher asigns him to make up a sentence and a word for the letter F. So the next day when the teacher asked him to read out his sentence and word he chose he replies with  the word I chose was FASTENATE. And the teacher very amazed by his big word gave him a round of aplause and then she asked what the sentence was and he replied by sayin,

"My sister has a red sweater with nine buttons but her tits are so big she can only FASTENATE".