About Scooby-DumScooby-Dum is a Blue (in the Cartoon) Merle Great Dane with a black mustache, flat eyebrows and a red cap. Dum lives with Ma and Pa Skillet, in the Okefenokee swamp of southern Georgia. Whenever Doo and Dum greet each other, Scooby-Doo yells, "Scooby-Dum," and Scooby-Dum says, "Scooby, doobie, doo." They then do a special handshake involving two high fives. Whenever he heard the word "Clue", he would invariably pull out a magnifying glass and, intoning the opening four notes of Beethoven's Fifth Symphony, chant "Dum dum Dum DUM!", even after a mystery is solved.
Scooby-Dum made his first appearance 25 September 1976 during the Scooby-Doo half of The Scooby-Doo/Dynomutt Hour, in an episode titled "The Gruesome Game of the Gator Ghoul". He appeared in one other 1976 episode of Scooby-Doo: "The Headless Horseman of Halloween", in which Shaggy referred to him as Scooby-Doo's brother. He made two appearances in 1977, when The Scooby-Doo/Dynomutt Hour was expanded into Scooby's All-Star Laff-a-Lympics: "Vampire Bats and Scaredy Cats" 17 September 1977, and "The Chiller Diller Movie Thriller" 1 October 1977, in which he was referred to as Scooby-Doo's cousin again thereafter. Scooby-Dum also appears in all of the Laff-a-Lympics segments of Scooby's All-Star Laff-a-Lympics as a member of the "Scooby Doobies" team, marking his final appearances in any medium.