Really how plausible/ possible is Gear 3rd?..
In any form in real life; just don't see it.
Alright, while I admit that this first one may not technically fit to real-life processes, how many times have we seen a cartoon character blow his/her hand/glove up to represent a large hand? How many times have we seen normal people do this? Also, if you consider that Luffy is made of rubber, and again what person in reality is actually rubber, Luffy's Gear 3rd is no different than blowing up a balloon (He even has an attack thus named). I also feel as if I saw a posting somewhere arguing these same points, but I can't seem to locate it.