Best thing - where do I start, driving's just so cool. Although it would probably be the time I tried to take a corner, where there was a nightclub with a large queue outside on a rainy Saturday night. Tried to take a left turn, the car began to slide on the wet surface until I was sliding sideways facing the turn I'd intended to take. A good bootful of throttle and the tyres bit, the car surged purposefully forwards, regaining control, and I was like "Yeah? I MEANT to do that".
Worst thing? Probably smashing up my Polo after hitting the first of two major floods behind a blind bend. That was my personal low. Although the worst thing from a legal standpoint is all the street racing i did when i was younger... I know I shouldn't be proud of it but, damn it, i am.