One Piece Chapter 18, page 17-19: Buggy, 'The Clown Pirate'

Luffy screams at the top of his lungs, 'I WILL NEVER FORGIVE ANYONE WHO MESSES UP THIS HAT!!!' Buggy is taken aback, asking, 'WHAT?' Luffy holds the hat tightly, declaring, 'THIS IS MY TREASURE!! I GOT THIS HAT AGES AGO FROM A FRIEND.' Nami watches Luffy's outburst in surprise, thinking, 'I THOUGHT THIS GUY WAS SOMEONE WHO'D NEVER GET AGITATED AT ANYTHING, BUT HE'S SO PISSED OFF NOW...!!' Buggy looks at the hat and asks, '....... IS THE HAT THAT PRECIOUS TO YOU? YEAH, YOU BASTARD!' He then swiftly prepares another attack.

Buggy throws his knife-wielding hand at Luffy again with a 'THROW' sound effect. Luffy dodges the initial strike, but Buggy's hand curves around in mid-air. Buggy shouts, 'IF IT'S THAT PRECIOUS TO YOU THEN WHY DON'T YOU PROTECT IT PROPERLY!!!' The detached hand flies directly toward the straw hat that Luffy is holding in his hand.

With a brutal 'STAB' sound effect, Buggy's knives plunge directly through the center of Luffy's straw hat. Luffy's eyes widen in absolute shock and horror. A brief flashback panel shows Shanks placing the straw hat onto young Luffy's head, saying, 'THIS HAT... IS MY GIFT TO YOU.