One Piece Chapter 1, page 9: Romance Dawn

Standing on the ship's bow, young Monkey D. Luffy holds up a small dagger and yells to the crew: "This is how tough I am!!! I've had it with you guys!! Now you'll have to take me seriously!!" On the deck, Yasopp, Lucky Roux, and other pirates laugh, shouting: "Ha ha ha! Get it over with! Whatever it is..." and "What's that pup up to now?" Suddenly, with a sharp "Chunk!", Luffy stabs himself in the cheek just below his left eye. The pirates' laughter instantly turns to absolute shock and horror. Shanks, Yasopp, and Lucky Roux scream in panic: "You idiot! What'd you do that for!?" while Luffy shrieks in pain: "Yeowww!!! Aaargh!!!"