One Piece Chapter 5, page 16: CHAPTER 5: THE KING OF THE PIRATES AND THE MASTER SWORDSMAN

Luffy lands directly in front of Zoro and Koby, stretching his body wide to block the incoming volley of bullets. The bullets hit his rubber chest with a rapid "BAP BAP AP PAP!" Zoro, Koby, Captain Morgan, and the Marines are completely dumbfounded, crying out, "YOU!?", "LUFFY!!!", and "STRAW HAT..." in utter disbelief.