Roast Beef is the name of a character in the online comic strip Achewood, drawn by Chris Onstad.
His place in the Achewood world is of the depressed tech support guy, reduced to making cries for help with crappy chimichangas and buying t-shirts with slogans such as "It is IMPOSSIBLE to have a good day," though he never wears thems.
Roast Beef, like the rest of the Achewood cast, is a stuffed animal-in his case, a cat. He has an older sibling named Ray (a party animal/swinger personality) whose hobby is to "get his bone on", and a younger sibling, simply named "little nephew." Since he is the middle cat, he was introduced as such, with the phrase
"Roast Beef, the middle cat"
"Not Ray and not Pat."