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. Here, in reference to needle 針 (はり), the ten can be seen as a needle, so this somehow expresses the feeling of standing on a needle.
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