The Legend of Korra, Season 4

Toph:
[giving up] All right, that's it. You're going to have to do this on your own. Clearly, you want to keep the metal in there.

Korra:
What do you mean? Why would I want poison inside me?

Toph:
I don't know! Maybe so you have an excuse not to go back to being the Avatar. If you don't get better, you can't do your job, so you don't have to worry about getting hurt again!

Korra:
Wha - that's ridiculous!

Toph:
Whatever. When you want it out, you can bend it out. I can't deal with all your issues for you.

Korra:
Wait! What am I supposed to do now?

Toph:
How should I know? Ask the spirit that brought you here. The good news is, if you're looking for a place to hang where no one will bother you, you picked the best swamp in the world!