Two spring to mind...
I lived in Vegas for 3 years in my early twenties and my housemate was a parole and probation officer (no, not mine...) He drove a big typical American classic caddilac and thought he was a bit of a smooth operator, despite being a lovely guy to boot.

We'd just had a game of tennis and were driving home when two young Mexican lads cut him up at a junction. Mike honked his loud horn at them and we continued on our merry way. Two minutes later as we pulled up outside the apartment they blocked us in the drive and pulled a gun on us. Mike luckily didn't panic and pulled his badge and they did a quick U-turn and fled.

Then I went to change my pants.

Secondly, as a 10 yr old my sister and I were taken to some freaky holiday resort called Fort Regent's in Jersey. They had all sorts of cheesy things such as a pretend submarine where you were attacked by some giant anglerfish on a screen, and a shark area where you'd walk along a corridor and see them all hanging up behind netting and every so often one would swing out to 'grab you'.

I got lucky and they swung down a giant Great White Shark to 'just miss' my skinny ten yr old frame. I was so scared my legs actually collapsed underneath me and my sister ran out of the place screaming blue murder while they tried to scrape me off the floor. As far as real sheer terror, that still wins funnily enough.
(Galahad is out of his gourd on yellow bentines, Wed 11 Apr 2012, 10:40, Reply)