"Potter! What are you doing?"
"Clearing up my armadillo bile, Professor."
-- Professor Snape to Harry, who was eavesdropping on his conversation with Igor Karkaroff during Potions (GF27)
Armadillo bile is a potion ingredient used in Wit-Sharpening Potion.
Harry spilled armadillo bile on purpose during Potions Class so he could eavesdrop on Professor Snape and Igor Karkaroff (GF27)
An armadillo is an animal with an armor-like outer shell for protection. The bile is used in Wit-Sharpening Potion.