noun
playing in the mud; mud play
Refers to children's play involving mud, often outdoors. The word 泥んこ is an emphatic or childish form of 泥 (mud).
See also: 泥遊び (どろあそび)
雨上がりに子供たちが泥んこ遊びをしていた。
After the rain, the children were playing in the mud.
My son, who loves playing with mud, always comes home with dirty clothes.