One Piece Chapter 2, page 16: THEY CALL HIM "STRAW HAT LUFFY"

Koby, remembering Luffy's words about fighting for his dreams, gathers his courage. He sweats and trembles but screams at the top of his lungs, "LADY ALVIDA IS......THE UGLIEST OLD HAG OF ALL!!!" Luffy bursts into hysterical laughter, "HA HA HA HA HA HA!" while Alvida's crew gasps in horror. Alvida is enraged, raising her mace as she screams, "YOU LITTLE--!!!" Koby stands his ground, shouting, "I SAID IT AND I WON'T TAKE IT BACK! NO MORE CRINGING FOR ME!! FROM NOW ON, I'LL FIGHT FOR MY DREAMS!!"