Goku meets Octopapa when he went the opposite way as Bulma and Krillin due to General Blue's trap. Octopapa gets mad at Goku when he mistook him for a spider and made him want to eat Goku. Goku ends up frying him with a Kamehameha, and eating him instead. According to Goku, he tasted like chicken.
Video game appearances
Octopapa is fought in Dragon Ball Z: Super Gokuden: Totsugeki-Hen. He appears during the boss battle against General Blue in Dragon Ball: Revenge of King Piccolo and Blue hypnotizes him to attack Goku; Octopapa attacks with his tentacles and by blowing bubbles at the opponent. He is a boss by himself in Dragon Ball: Origins 2 where he attacks with one of his tantacles and causes rockfalls. In the bonus level 3-6, Bulma goes in the underwater cave alone to find the octopus, because it contains a nutrient that make the skin beautiful.
Octopapa (named Giant Octopus) was somehow reincarnated in Dragon Ball Z: Attack of the Saiyans, guarding the Five-Star Dragon Ball in the Pirate Cave. Goku comments that he is a squid to which Octapapa replies: "Why do I feel like I've had this conversation before?", referencing his first encounter with Goku. He also reveals that he was told to guard the Dragon Ball by the Red Ribbon Army.