"The Big Brain am winning again. I am the Greetest."
"Now I am leaving earth for no RAISIN!"
(Reason was probably spelled by Fry as Raeson. "RAE" can sound like "ray". But the result is he sounds like he is saying raisin. Which makes it hilarious.)
I also like from that same episode
"Ooh, Tom Sawyer, you tricked me. This isn't nearly as fun as you previously indicated."
"I'm a GIGANTIC BRAIN!"
"The Whale, he be white now."
Leela: Brain, Brain make people dumb.
Fry: No Leela, brain make people smart. pffft.