My Ex was the same
Her dad was a Captain in the Merchant Navy, therefore I couldn't possibly do anything without her fathers approval, admittedly he did know the score and just went with my idea (maybe mentioning a few tips to me privately if required).

The classic one being:
I bought a SAAB 93 a couple of years ago, and when you park it you have to put it into reverse before you can take the key out, it gets Thatcham one for that little gem, anyway she was convinced this was dangerous and that the car would roll down the hill if parked facing upwards and the handbrake failed for some reason. I tried with all my reasoning skills that this wasn't going to happen to no avail.

Her dad however pulled it of with 1 sentence: 'do you know how steep the hill would have to be to get a 1.5 tonne car that's in reverse gear to start moving backwards down a hill?' and that was it, she just accepted it and then when I protested apparently I didn't explain it properly!?

He never finished the sentence, shame really, I'd love to know the answer and he'd probably be able to work it out too, I miss the random conversations we used to have.
(Kip, Wed 30 Dec 2009, 17:25, Reply)