The Tango Beast is a mythical creature confronted by Jack some time before the episode he appeared in. He is a green, dragon-like creature with light-blue rings of fur around his neck and tail and a pink snout.
During the battle, he left a scar across Jack's chest that was later a clue for the Scotsman to finding what had happened to Jack's memory and sword. The Scotsman remarks that the best way to draw it out is with the stench of the "wily jub-jub plant."
The Tango Beast is mild-mannered and docile after his confrontation with Jack. According to the beast, he was confronted by Jack because he was terrorizing a town "because it made him feel better about himself" due to his low self-esteem.
After his fight with Jack, his life seems to have improved. He has his old job back, is more outgoing, and claims to have improved his hygeine. That last one seems debatable as the Scotsman still thinks his stench could knock a man out.