In the book Frindle the boy Nick Allen made up the word frindle. His friends say an oath to not use the word pen instead use the word frindle. Next they say the word frindle at school and all the fifth graders are using the word frindle. Soon the whole school uses the word frindle and Ms Granger the teacher makes them write 100 sentences "I will use the word pen". Then Nick becomes famous and rich for making up the word frindle.
I would recommend you read or listen to the story on CD. I liked the story because he made a word up and his word was in the dictionary with thousands of other words.