When I was a little kid, I received as a birthday present a purple notebook emblazoned with the Hogwarts crest. Featuring the four houses of Hogwarts in red, yellow, green, and blue respectively, the crest also had the Hogwarts motto printed in capital letters: DRACO DORMIENS NUNQUAM TITILLANDUS. I always assumed that this was some magical spell that JK Rowling never had the time to explain in the books, but much later in my life I realized that, just like many other names and phrases in the Harry Potter universe, there is an inside joke buried in this motto.