@Willpower:
If his whole body is made of rubber like you said that doesn't answer my second question and other questions I might add too..Like how does he break rocks with his fists and do incredible damage with them (before timeskip) so don't tell me oh look he's using armament haki..
So the answer is either unknown which will lead us to: One piece logic
Or it was already answered in SBS
Does anyone have a good answer for this question please? I'm very persistent when it comes to logical problems..Like this one in particular.
I just try to think of all the different types of rubber that there are. Rather than thinking of Luffy's body like a rubber band, think of thinks more along the lines of tires, rubber mallets, or hockey pucks (which feel a lot less like rubber and a lot more like a friggin' rock). So take the elasticity and snapping power of a rubber band, and assume Luffy's bones are an incredibly dense and hard rubber (ie: fists and teeth), then the destructive power starts to make more sense.
Luffy's armament haki also makes his body look like it's become vulcanized rubber (which is a hardened, black form of rubber used to make bowling balls and other things), so he just becomes that much harder. Although that's probably not the case since everyone turns black when they use Haki.