anal penetration/torture (buttock from the side 尸, opening/anus 口, needle 辛 as symbol for penetration or torture) [Actually 針 stands for needle and 辛 is understood as the image of a tattoo needle that also stands for: bitter.]
Is composed of standing 立 and ten 十. In reference to "needle" 針 (= はり), the ten can be seen as a needle. Thus, somehow the feeling of standing on a needle is expressed.
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