Berlin - hotter but better

Just back from an ill timed weekend back in London, a city which doesn't do heat well. Stuck inside the sixth circle of hell, otherwise known as the northern line, I had plenty of time to reflect that although I missed the place initially, any desire to move back has by now disappeared. In fact I find myself muttering out loud 'how on earth did I live here' as I traverse the city.

What is that law of physics that says every single time you do a journey something in your washbag has to leak all over the entire contents of your luggage?