'Doc Boy' Arbuckle is Jon's younger brother, who lives on a farm with his mother and father, and often fights with Jon, calling him a "cappuccino-sipping city slicker", and worse. He hates being called "Doc Boy", but puts up with it (this was revealed to be a result of him starting to wear long pants, the Thursday before this was revealed).
Doc Boy is just as immature as his older brother Jon. He is far more out of touch with fashion than Jon. He is alos even stupider than Jon. Unlike his brother, Doc Boy likes mice. Although he is generally ignorant of urban life, he did have one astute reasoning to remain on the farm.