Well it´s that time again where I´m having an utterly whack idea and writing it down to share with everyone else. So this is your last warning, only read further if you don´t want your head to hurt!
Ok, I´ll get to the point now. Back in the Skypiea arc we´ve seen a priest riding a fire breathing bird and wielding a lance that could set things on fire. It was some unseen things until then in One Piece. Later on Gan Forr however revealed the trick behind the fire breath or the heat lance. It was simply dials. They weren´t visible but they were there. That´s the one thing.
However, we learned in Skypiea that there once was the Jet Dial that doesn´t exist anymore. But would Oda really talk about such a Dial if it´s not going to get shown at some time? I think not. I´m sure that it´ll appear sooner or later in One Piece.
Ok, so far the theory doesn´t seem that whack after all. So let´s get to the real point of whackness…Gear 2nd. We´ve seen Luffy calling his Gear attacks Jet Pistol and Jet Bazooka. How come so? What is the power behind Gear 2nd.
Well, what if Luffy is using the power of the Jet Dial. It could be somewhere in his body and what happens on the last panels of this page is actually the effects of it on his rubber body when it gets activated. And then there´s this thumb thing. Could it be that he was going to press the apex?
Where did Luffy get such an ancient dial from? Well, who knows what all was laying around in the python´s stomach. Luffy could have found it and thought it was food. No idea.
Well that´s about it. This is not the theory that I´m going with myself, but since the thought already occured to me, I didn´t see why I shouldn´t spread it. Even if it sounds completely whack. Don´t hit me! XD