S6E23: The Tip of the Zoidberg
DR. ZOIDBERG: What the hell are you doing?
Zoidberg, we know about your secret agreement.
I am so, so sorry for how we treated you.
And to make it up to you, we're killing the Professor for you so he doesn't die horribly from hyper-malaria.
He doesn't have hyper-malaria, you idiots.