He grabs his belly and yanks off a piece of it, stretching the skin to make it long. The skin suddenly comes alive, and Majin Buu can use it as a weapon.
Majin Buu can use the Potbelly Attack in one of two ways. The first method involves Majin Buu detaching a piece of his belly and swinging it around violently, sending a giant exploding ki orbs at the opponent. The second method involves Majin Buu throwing his detached belly at the opponent, constricting them tightly. This attack is powerful enough to hold the strongest of enemies. It is devastating against regular humans, as they will be crushed to death in the coils of the skin within a matter of seconds. The skin will continue to crush the target until someone pulls it off or the victim is strong enough to escape.
Majin Buu used this technique during his fight with Majin Vegeta. Buu used the ki orb method first and Vegeta to have to move quickly to evade the blasts. While Vegeta was distracted Buu blasted him with his Ill Flash which caused the Saiyan Prince to fly quickly into the air allowing Majin Buu to throw his detached belly at him, wrapping him up.
With the Saiyan wrapped up and immobilized, Majin Buu then proceeds to crush him under his huge body and beat Vegeta senseless. It wasn't until Trunks and Goten stepped in, that Vegeta able to be freed from the attack.
Video Game Appearances
In the Dragon Ball Xenoverse series, the technique appears as Majin Buu's standard throw, where he throws a piece of his flesh at the opponent, if it hits the opponent they will become wrapped up and immobilized, Majin Buu then uses Rapid Movement and reappears to kick the helpless opponent. Male Majin can also use it as their throw in Xenoverse 2. In Xenoverse 2, it uses the same effect animation for ensnared opponents as the Go-Go Gum Super Skill.
In Dragon Ball FighterZ, it appears under the name Fat Throw as one of Majin Buu's Special Moves.