Your mouth doesn't "think faster than [your] brain," you either have an impulse control disorder or- more likely- haven't bothered keeping your impulses under control. Then you use your lack of self control as an excuse for saying stuff that is rude and cruel- because if you know you do it, there's no reason for you to have been NOT working on improving it. Your mouth is a mouth. It can't think for itself. Blaming it for saying rude shit because you have no manners or empathy. It's like trying to pass the guilt for a murder you committed onto your hand because it thinks faster than your brain. (Barring alien limb syndrome, of course.)