This was drawn for me as a surprise by  jedders.

The raccoon is Mister Raccoon, a "puppet" on furrymuck. He was programmed to mimic lines that are said.

Well, Dipper would invariably get a candy bar from a vending machine that  jedders had in his room and then nibble it. After a while, Mister Raccoon would mimic that, every time Dipper got a candy bar, thus stealing it from Dipper. Dipper obviously didn't like that.