Luffy coats his arm in Armament Haki before biting into his forearm. Then he blows an incredible amount of air into his body, but this time Luffy does not significantly expand, with his forearms, legs, and only his upper torso being only slightly enlarged, Luffy's hair becomes flame-shaped like his Haki and sticks up. Then once the gas clears, He looks at you.

"Gear 4: Snakeman!" Once Luffy finished his transformation, he stood in place and gets ready to take you on