User blog comment:Torquil/What should Luffy's gear 4 be like? ?(If you think he is going to get one...)/@comment-4577739-20121217170738

Pshhh, I'll just bet on some kind of thing were Luffy uses his Haoushaku haki to take control of his body, forcing it far past the limit. Hes Rubber so his limiyts are stretchy, lol when he breathes he'll be like giant and then he breathes out and back to normal. Since his haki has taken control of his body his body can go crazy creating death weapons on his body or something.

Meh