The revealing pants, known in Chinese as "kaidangku", used to be a popular sight on the streets. But now more parents, buoyed by a more sophisticated lifestyle, are turning to disposable nappies instead. The Chinese government has also been trying to encourage an effort to spruce up its urban areas and, it says, steer people away from unclean practices. Many cities have outlawed indiscriminate rubbish dumping, public urination and street spitting. The "kaidangku" are split down the middle - in front and back - and provide what many parents say is maximum convenience with minimum coverage. Although the origins of...