Society's decline into anarchy is symbolised by the slide of the trouser waistband from somewhere near the belly-button to halfway down the thigh.
This occasions the exposure of a considerable expanse of underpant, formerly a private garment, seen only by the wearer and his spouse or therapist.
It's thought the comical practice originated in US prisons, and signified the male wearer was available for extra-curricular activities.
Today, it just means you're a nutter.
It's particularly funny to see middle-aged men indulging in this crime against gravity.
They must decide: "I'm going to drop my trousers six inches, like the young people do".
This is similar to the way that many citizens, subconsciously perhaps, decide to change the way they speak by adding an interrogative inflection at the end of sentences (is that dying out, by the way?).
However, there are signs - literally - that civilisation will tolerate these trousular abuses no longer.
A Manhattan judge has put up a sign in court ordering young people to pull up their 'pants', as Americans mistakenly call trousers.
Justice Eduardo Padro told one hoodlum: "I have no interest in seeing your behind."
It was a controversial remark for a judge to make, and sparked rioting in several rural areas.
But the point had to be made.