I've never really been into drugs. I dabbled in hash and speed when I was younger, but only if it was in the vicinity. I drink, but hardly to excess. The closest I've ever come to addiction was my caffeine habit, and I've pretty much broken that now.
Yesterday, however, I discovered a new, natural, legal high. Unlike banana skins, it works, and unlike morning glory seeds, it doesn't give you bizarre flashbacks for months afterwards. All you need to do is to walk around Bangkok in the middle of the day, at the height of the hot season, well away from any air-conditioning or shelter. After a few hours, everything starts to ache and you feel as if you're running in treacle. The fortunate thing is that this stage (the equivalent of the comedown or the hangover) comes first. The following day is spent in a spaced-out trance, where everything is three steps sideways from reality and the most peculiar songs leap undbidden from the depths of your memory.
And best of all, if the Thai authorities stop you at the airport with half a kilo of heatstroke up your bottom, they can't do anything. Although they may ask to share it.