Gum-Gum Balloon

Gum-Gum Balloon is 's down special move in Super Smash Flash 2.

Overview
When performed, Luffy will puff himself up for a moment, dramatically expanding in size before shrinking back to normal. While it deals no damage to opponents hit, Luffy will have a windbox the moment he first inflates that pushes opponents near him away, and while inflated, Luffy will gain heavy armor. When performed in the air, the move will cancel his previous vertical momentum and he will float slowly through the air, which can help him recover horizontally. He also will perform a small jump after finishing the move as he deflates, though the jump becomes smaller every time he uses it.

Origin
Gum-Gum Balloon is a technique used in One Piece where Luffy inflates himself rapidly through his mouth. Much like in SSF2, this further increases his resistance to blunt attacks. With his inflated body, Luffy is capable of deflecting projectile attacks back at his attackers. This is not necessarily always an attack as Luffy can also use this technique for other purposes aside from deflecting projectiles such as escaping Smoker's Smoke Snake technique or using himself as a cushion when his ship is in for a hard landing. This can also prevent Luffy from sinking under water, making him bounce off the surface.