Arlong's Arc. When Sanji, Luffy and Johnny left the Sea Restaurant for Arlong's Park, Sanji cooked up a tasty dinner that attract that big sea monster that was one of Arlong's cronies. So Luffy attacks it and get it angry. But what was real funny was when Sanji was trying to appease it with the food. I thought he was being nice to the sea creature and apologize for Luffy but all of a sudden he boots him. The face on Johnny's face from seeing them beating the sea monster was just priceless. I cracked up so much...
