Gear Fourth is one of Monkey D. Luffy's signature transformations in One Piece, first used during his battle with Donquixote Doflamingo in the Dressrosa arc. The form combines his rubber body with Armament Haki, letting him bounce, compress and strike with far greater force than his earlier gears. Clips of the transformation quickly spread through anime edits, reaction videos and soundboards, where the power-up became shorthand for a sudden escalation. It remains popular because it marks a clear turning point in a fight, giving creators an instant way to signal that a character has stopped holding back.