1.) Not to be confused with a SweatHog the ButtHog term is bestowed selectively upon a person whom has reached a level of friendship that the either party involved may refer to the other as a "ButtHog" as a casual way of calling a friend a pervert or one who obsesses over posterior ends or commonly referred to as an "ass" or "butt". Ultimately the namesayer may be the perverted one, making some sort of insinuation.
2. A Butt Hog.
Frank insessintly watches porn that is specific to Ass or Butt Fetishes. An acquaintance of Frank's, Ted, takes notice of Frank's natural fetish & has reached an intellectual level with Frank & so decides to utilize the term & Ted says: "Frank, You're My Sweet Little ButtHog"
Also see SweatHog