Farnsworth is my second favourite character (after Bender and tied with Fry, followed by Zoidberg and Zapp) and nearly every line the senile old man says is a crack up ( in fact, I also made this thread - Good News Everyone - but it was over a year ago).
There are way too many cla$$ic lines to list so here are a couple of my favourites:
Farnsworth: We'll need to speed up their growth with time particles called Chronitons.
Bender: Aren't those the particles that destroyed an entire civilisa-
Farnsworth: Good news, everyone! You're off to the Tempus Nebula to gather Chronitons.
Farnsworth: Start the ship, Leela. Let's just steal the damn radar dish and get back to our own time.
Fry: But- But won't that change history?
Farnsworth: Oh, a lesson in not changing history from Mr. I'm-My-Own-Grandpa! Let's get the hell out of here already! Screw history!