I agree with you about Katara's mocking being funny, btw. I loved how they animated her face for that scene, and the way the actress delivered it. I thought most of the mocking in this episode was funny. Even the harsh "not as good as you thought" was funny because it was something everyone's experienced before: a single beat where everyone else is silent while the words hang and it's WOW AWKWARD TURTLE. Then it's Toph.

One of my favorite line's was Sokka's insulting "Hey jerks...jerkbending." I think I found that so funny because he included Aang in the "jerks" category, and didn't make disclaimers or anything.