One Piece Chapter 20, page 8: A Thief's Philosophy

Luffy sits down and tickles Buggy's captured foot. Buggy's flying head suddenly feels the tickling and bursts into uncontrollable laughter: "PUHEHEHEHEHEHEHE... ST... STOP... KUHEHEH!" Nami is bewildered. Luffy then pinches and cracks Buggy's toes, causing Buggy to scream in pain: "AAAAAAHH...!!" Nami gasps in shock.