One Piece Chapter 1, page 13: Romance Dawn

Yasopp and another pirate try to convince their captain: "C'mon, Cap'n... Let's take the lad with us just this once..." Shanks smiles slyly: "Okay, but one of you will have to stay behind..." The crew immediately backtracks, laughing: "Sorry, laddy, you've just been benched! Let's drink!" Luffy grumbles: "Hey!! I thought you guys were on my side!" Shanks tells him: "You're just too young, kid. Maybe in 10 years I'll give you a chance." Luffy yells: "I'm not a little kid!!" Shanks tries to soothe him: "Don't get upset now. Here, have some milk." Luffy happily drinks it: "Oh boy! Thanks!" Shanks immediately bursts out laughing: "See! A real pirate would never drink milk!!" Luffy slams his cup down, furious: "That was a dirty trick!"