One Piece Chapter 2, page 21: THEY CALL HIM "STRAW HAT LUFFY"

An explanatory page titled "STEP 1: THE PIRATE FLAG" provides historical trivia about the Jolly Roger. It explains that the skull and crossbones represent thigh bones and that the flag is a symbol of death. It lists three theories for the origin of the term "Jolly Roger": 1) from the French "Jolie Rouge" (Red Lovely), referring to blood; 2) from the word "Rogue" meaning a thief or villain; 3) from "Old Roger," a traditional name for the devil.