We all know that we shouldn't swear in the public, or even in front of the elderly. But on some cases, we don't think to swear. On things like accidently dropping your favourite phone to the hard ground, or a sudden bump when you are driving made you blurt out the f-word or s-word without thinking much. I've checked with some of the old Neurobiology notes I have under my bed, and also this website: How Stuff Works - Swearing and the Brain and confirms that swearing is a lot to do with impulses, and not on thoughts. Our brain is a really strange computer. Our head doesn't process and judge everything!