Choo-Choo Bear is a "boneless" (technically, Choo-Choo Bear's skeletal structure is sufficiently gelatinous for him to simply appear boneless) and hairless cat (due to, respectively, an unexplained "rare bone disease," and chemotherapy). As a kitten he had yellow and brown fur.[1] He had a cousin, Twitchy-Hug, who...um...exploded. Choo-Choo Bear is Jewish.[3]