He is off-white and has many black spots on him. He is a friend of the Gorilla. He somehow lives under-water. He also must be quite strong because he can hold a gorilla.
Role in the episode
He appears at the end of "I Had an Accident" and George gets on top of him, and they ride off in the sunset. George partially causes the ending of the episode, 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 is actually two people in the costume.