People telling lies, or more importantly people not putting any thought into the lies they tell. I work in a profession where there is an element of enforcement. People have to give accounts of what they have done, now I don't mind an elaborate storey which is difficult to pick holes in but it annoys me when they tell outright lies which are obviously not true.
Politicians do it all the time, they say things and then when what they have said doesn't suit their purpose they start this "it is being taken out of context" or "what I said is being misconstrued". Utter lies.