Two

Ths mad cat is called "Two", primarily because the other cat is called "yellow" and you cant have both of them called numbers!
Comes from having your toddler naming the animals and a long day of being endlessly asked "what colour is this called?" and "how many of them can you see?"
Fifteen years later we still debate vigorously who has to take the cats to the vet, as it is so embarassing to have the vet come out and call out their names. In fact I dont think that Two has been for years for that very reason.