Have just read the thread on thinking about sex whilst running.
Better than that is 'sneaking', which for those not initiated in the pastime, is going for a run after dark, stripping naked, then running home in the nuddy.
As a thrill seeker, it's hard to beat.
Can't do it in town centres (that's called streaking), and remote countryside doesn't really count either - the trick is to dodge behind cars or into gardens on the way home to avoid being detected. Summertime is also the best time of year.
For best effect try it with your best (opposite sex) pal.
Prize for the best report by the end of the week.