Also known as: スパンキング, お尻ペンペン, お尻ぺんぺん, お尻叩き, 打尻, 打屁股
Slapping someone's Ass with a hand or some other tool, as a form of punishment or erotic roleplay.
If the ass is red or marked, include the Spanked tag as well. If the person is in position to be spanked, but hasn't been spanked yet, use Imminent Spanking.