Open-crotch pants

Open-crotch pants
Chinese boy wearing open-crotch pants at a park in Beijing
Traditional Chinese	開襠褲
Simplified Chinese	开裆裤
Literal meaning	Open-crotch pants
Transcriptions Standard Mandarin Hanyu Pinyin kāidāngkù Yue: Cantonese Yale Romanization hoi1 dong1 fu3

Open-crotch pants (simplified Chinese: ; traditional Chinese: 開襠褲; pinyin: kāidāngkù), also known as open-crotch trousers or split pants, are worn by toddlers throughout mainland China. Often made of thick fabric, they are designed with either an unsewn seam over the buttocks and crotch or a hole over the central buttocks. Both allow children to urinate and defecate without the pants being lowered. The child simply squats, or is held by the parent, eliminating the need for diapers. The sight of the partially exposed of kaidangku-clad children in public places frequently astonishes foreign visitors, who often photograph them; they have been described as being "as much a sign of China as Chairman Mao's portrait looming over Tiananmen Square."

In China they are often seen as a relic of the country's rural past, with younger mothers, particularly in cities, preferring to diaper their children instead. However, Western advocates of the elimination communication method of toilet training have pointed to the advantages of their use, specifically that children complete their toilet training more quickly and at an earlier age. Other benefits claimed include the elimination of diaper rash and reduction of the environmental problems caused by disposable diapers. Some Western parents have even begun putting their own children in kaidangku.

Toilet training begins very early in China, sometimes within days of birth and usually no later than a month. Frequently babies are held closely by parents, grandparents or other extended family members caring for them, sensitive to when they need to relieve themselves. A child who appears ready to urinate or defecate is held over the toilet or any other receptacle available if a commode cannot be reached in time. The adult makes a high-pitched soft whistle while holding the child in a bă (Chinese: ), or bunched-up position, a term sometimes used for the whole process, imitating the sound of running water or urine, to get the child to relax the appropriate muscles.