'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", although he puts up with it. According to his father, this is a result of him starting to wear long pants, which occured the Thursday before he disclosed the fact.
Doc Boy is just as immature as his older brother. He is shown to have a worse fashion sense than Jon and is sometimes portrayed as less intelligent. Unlike his brother, Doc Boy likes mice.
Although generally ignorant of urban life, he does have one astute reason to remain on the farm: He figures that since he ultimately chose to stay on the farm while Jon moved to the city, he will inherit the farm from his father, sell the property, make a huge profit and retire while still young.
- Home for the Holidays Part 2
- Farm Fresh Feline
- With Four You Get Pizza (cameo)
- Everything's Relative
- Delicious Donut Day (mentioned)
- This character is based on Jim Davis's real-life brother, David "Doc" Davis.
- He has appeared 59 times in the comics, the 27th most.
- Doc Boy is Jon's only known sibling, and is confirmed to be his only brother. Nevertheless, Jon is shown to have a number of nieces and nephews, indicating that Jon and Doc Boy have other siblings outside of each other.
- He still sleeps with a "blankie", as revealed in comic strips in November 29, 1984 and July 24, 2003.
- The "boy" part of his name is likely a reference to John Boy from The Waltons.