He is off-white and has many black spots on him. He is a friend of the Gorilla. He somehow lives underwater and must be quite strong since he can hold a gorilla.
Role in the episode
He appears at the end of "I Had an Accident," when George gets on top of the Gorilla, and they ride off into the sunset. George partially causes the ending of the episode, with the watchers being weirded out and turning the TV off.
George is possibly a horse, not a zebra, because he has spots on him instead of stripes and the fact that horses are meant to be ridden on, rather than zebras.
The zebra/horse contains two people in the costume.