Ooooh, it's raining!

What is it about people that turns even the most reasonable of them into inconsiderate, myopic dickheads as soon as they put up an umbrella? Probably the same thing that makes them drive like morons as soon as it starts raining. The next umbrella that comes within a metre of my face gets shoved up the arse of the person wielding it, sideways. Have I made myself clear?