One Piece Chapter 8.3, page 4: Nami Enters

Suddenly, Luffy spots something in the sky and exclaims, "OH! A BIRD! LOOKS PRETTY TASTY... LET'S EAT THAT BIRD!" Zoro looks up skeptically and asks, "HOW ARE YOU GOING TO EAT IT...?!" Luffy confidently replies, "I'LL GO GET IT! WATCH MY SPECIALTY!!" He grabs the sides of the boat, stretching his arms back as he prepares his attack. Calling out "GOMU-GOMU..." he launches himself into the air like a slingshot, shouting "ROCKET!!" as he flies straight up toward the bird.