Help an old ladie cross the road, making it look all sweet and helpful - but while you are crossing the road, call her a fat slag as many times as you can.
Obvious ones if you haven't done them already: Music festival, preferably outside the UK Travel the UK without plans for places to stay each night Hallucinate (legally if you're so inclined) Form a band Not think that you have to stop once you hit 20.
Go paragliding. Go White water rafting. Go canyoning. Go to the top of Mount Everest. Go to Egypt. Go Skiing. Have a threesome, the cool kind. Go Sky diving.