#1376: when you get near your front door, it's likely that you suddenly need the loo - dubbed "key-in-the-lock urgency", this is thought to be a case of classical conditioning, like Pavlov's famous dogs. what's interesting is that some are thinking that this mechanism can be used to treat and prevent Over-Active Bladder Syndrome, by negating these psychological conditions or even reversing them. running water also triggers a strong Pavlovian response (you'd expect stronger than key-in-the-lock because it's pretty much every time you go to the loo, ever) - but it's also thought to have a physiological effect too, relaxing your bladder muscles or something like that.