Badgerfrog

Description
This furry, hopping animal is indigenous to the Western Fire Nation. At first look, the badgerfrog seems cute and harmless, but if cornered by a predator, it will defend itself by hopping, clawing, and biting angrily. Badgerfrogs have been found to be strangely attracted to earnest monologues delivered by weary travelers who stop to camp in their habitat.

It is first seen when Zuko practices his introduction to the Avatar's group in "The Western Air Temple". During "The Boiling Rock, Part 1", Zuko instructs Aang in a letter to do a series of exercises every time he hears a bagderfrog while he's away, causing Aang to complain that "nobody else has homework".