お尻しりぺんぺん

noun, noun or participle which takes 'suru'

spanking (a child); a light smack on the bottom

A mild, often playful spanking given to young children as discipline or warning. The term is informal and typically used in family settings.

• いたずらをしたら、お尻しりぺんぺんだよ。

  If you misbehave, you'll get a spanking.

• 母ははは弟おとうとにお尻しりぺんぺんをした。

  Mom gave my little brother a light spanking.