Off with his hat is an episode of Flapjack where Flapjack and K'nuckles go to a secret swimming hole and K'nuckles loses his adventurer hat because it is stolen by a chimpanzee named Cameron. Flapjack and K'nuckles are then kidnapped by the chimps and taken to there village to be possibly sacrificed, but then a mysterious woman in love with K'nuckles helps him find his hat at the "secret place". But K'nuckles must walk across some vine that is over an active volcano. K'nuckles eventually gets his hat back, but the woman says he destroyed all her years of research and tried to tell the Chimpanzee Leader to throw the hat into the lava but K'nuckles throws her into the volcano and she shoots out all the way to another island.
This was more similar to The Penguins of Madagascar episode, Crown Fools. Both King Julien and K'nuckles lost their hats. It also tells about "Beat the king, get the crown" challenge.
Music from "Plankton!" can be heard in the title
We learn that K'nuckles got his adventure hat when he was younger.