One Piece Chapter 1.1, page 26: Romance Dawn (Version 1)

Shiruku covers her ears and screams in terror, "KYAAAAA!!". Gyari laughs triumphantly, "GYAHAHAHAHAHA!!", believing he has won. However, the bullet hits Luffy's chest, but instead of piercing him, his rubber skin stretches deep inward, absorbing the impact. Luffy grins and flexes his chest, shouting, "FUHN!!!". The bullet is launched backward, flying past Gyari and his shocked crew. Gyari's jaw drops in absolute disbelief, sweating profusely as he stares at Luffy.