User blog comment:Kaido King of the Beasts/Chapter 784 Prediction: Gear Fourth/@comment-25926617-20150419235703/@comment-25926617-20150420015147

Usopp grows his pop greens on the ship. another theory i have seen is Luffy gathering a lot of his rubber body into one spot, such as his arm, then releasing it. Being super fast and powerful. these are the two best i have heard.