Author's Note: Snape gave many indicators to the class that Lupin was a werewolf that Hermione picked up. But when he came into Potions class one day singing this song, this was really what drove the point home for Hermione. Unfortunately, the rest of the class was so stunned about the fact that Snape was actually singing, they didn't listen to the lyrics.
Lupin the Rabid Werewolf
Lupin the Rabid Werewolf
Had a very black wet nose,
And if you ever saw him
You would shout and scream "Oh no!"
All of the other wizards
Used to scream and run away!
They never let poor Lupin
Join in any teacher games!
Then one foggy Hogwarts eve
Dumbledore came to say,
"Lupin with your brain so vast,
Won't you come and teach a class?"
Some reason the students loved him
Even though he was a freak
Lupin the Rabid Werewolf,
You'll be outta here next week!
Unfortunately for Snape, he wasn't.
...Also, Lupin's a werewolf. Hope you kids got that. It was the point of the song...