Mr Bumpy's Brain
Mr Bumpy's Brain is a character and the third organ that Mr Bumpy and Squishington encounter in the episode "Gum Crazy." He is voiced by Jim Cummings. 

The Brain is tiny with a mouth and eye stalks similar to Bumpy. He is a small insignificant creature, but is very greedy like Bumpy and is obsessed with gum. 

Bumpy tells the Brain to give him the gum or the world will be destroyed, and he also wants it. A loud booming voice is heard on top of a large pedestal, saying "never ever ever", Bumpy then leaps up onto the high pedestal and see's his brain sitting on a throne, revealing his actual size.

Bumpy says that he expected him to be taller, the Brain demands gum and uses his tail like brain stem to grab the jar. Bumpy and the Brain start fighting over the jar, Bumpy tells the Brain to give him the gum, but the Brain says he doesn't have any, they start arguing like little kids and continue fighting.

When Squishington points out to Bumpy that he had the gum the whole time, Bumpy realizes that he has been fighting himself the whole time. Bumpy then becomes tranquil and says he doesn't need the gum, the Brain shouts out that he is lying and slaps him in the back of the head.