Why?

Why do people start to slow down half a mile before they make a right turn? Why don't they slow down closer to the corner? And why is it that when you think you should make a security visit to the restroom before a lovely outing, you think "No I'm fine I don’t need to go," but then five minuets down the road your body’s going "Ha-Ha who needs to visit that porcelain bowl now?" Why would your body play tricks on you like that?
And why on earth is a Chihuahua a dog? It looks more like a rat.
Why?