Emergency Stop.

I learnt to drive quite a few years ago, and apart from getting some serious mental blocks when it came to actually passing the test, I picked it up very quickly.
I had an excellent driving instructor which helped. Patient, practical, always calm and brilliant when it came to explaining things to me, I reckon it was mainly thanks to him that I've never caused an accident when out on the road.
Over the years I've had some close shaves such as the time some pr@ reversed out of a driveway in front of me without looking, and the time a cyclist with no lights on the bike came hurtling out of the rain and dark doing about thirty, but again, thanks to his tutelage I've avoided killing anyone. Well, not while driving anyway.
The whole point of this tale is that what he told me has stuck in my brain, and one lesson more than any other; that of the emergency stop.
It was a gorgeous late spring day, the sort that has that first whiff of summer in the breeze, and he'd picked me up early so that we could practice driving around a local estate before the traffic set in.
Despite the rain the previous night, the day was warming up nicely and we opened the windows so that the air wound round us in the car to freshen us up. I did a few three point turns and reversed around a couple of corners before he decided I was ready to try my first emergency stop. He told me to drive along the road at a steady thirty, and that at any point he was going to hit the dashboard and say 'Stop!'. He asked me if I was ready to which I replied 'yes', and as it was getting warmer by the minute he opened the sunroof before we set off. We pootled around for a while as he waited for the right moment to stop, being one with no oncoming traffic or cars tailgating me, and we both started to get a little lackadaisical as the sun streamed into the car and lulled us into it's ever increasing warmth.
But then he found the right moment.
"Stop!" he said as he hit the dashboard.
"Aaaaargh!" we both yelped as the rain from the roof of the car drenched us down the back of our necks as I slammed the brakes on.
"Shit!" cried the instructor as my foot hit the accelerator in my panic.
"Aaaaaaargh!" I screamed as we hurtled towards a parked car.
"Mwaaaargh!" we screamed as we both hit the brakes at the same time causing the car to stop inches away from the parked car.

There were a few moments of stunned silence as we sat there, wet, and now totally wide awake.

He then began to apologize profusely as I sat there, soaked, but then I got the giggles, which set him off giggling too.
After a ciggie break, he told me that my emergency stop had been just fine and we'd leave it for a while before trying it again.
To this day, I have never opened a sunroof while driving, just in case.