One Piece Chapter 30, page 9: GREAT!!!

Luffy throws his arms in the air and lets out an incredibly loud roar: "YEAAAAAAAAAHHHHH!!!" He has accidentally been hypnotized by Jango's pendulum as well! Zoro, Nami, and Usopp are completely flabbergasted, with Zoro screaming, "YOU GOT HYPNOTIZED TOO?!?" Jango is also taken aback, sweating as he thinks, "EH!? HE'S NOT YOUR AVERAGE IDIOT... GOT HYPNOTIZED SO EASILY..." The hypnotized Luffy charges forward alongside the pirates, roaring.