Season 1
I.M. Weasel is highly intelligent, and is skilled in most if not all known professions. He is also incredibly charming and well-versed in the social graces, and will often have a pretty girl at his side.
Weasel's only real flaw is a secret desire to suck the yolk from eggs (though such behavior is actually a characteristic of the mongoose family, which is of a different order of mammals than weasels).
In contrast, I. R. Baboon is considered dim-witted and slovenly, uses incorrect grammar when he speaks (for example, I. R. stands for "I are"), and is very jealous of Weasel's success.
He is often shown doing the opposite of what would be considered sensible, and sometimes displays obsessive-compulsive behavior. I. R. Baboon has few skills but was discovered unexpectedly to be a virtuoso on the theremin.
Baboon wears only a T-shirt with a handwritten, inverted "I. R."
His protruding red butt is often highlighted and serves as a focus of others' ridicule.
He attempts to outdo Weasel at everything, and when he believes he has succeeded, he performs a routine victory dance, placing his hands on his hips and jumping around in a circle while repeatedly chanting a declaration of his success.
In some of the episodes, Weasel and Baboon are actually friends and work together