「Screwing in spread legs」likely needs no further explanation, other than to note that the Chinese given external meaning refers the reader to the glyph meaning PADDED, PADDING of some sort. Elements as「rod horizontal in loincloth」also may denote a large bulge of the PADDING used in a poultice to catch the continual drip, drip, drip of gonorrhea, known in the West as a「codpiece.」…or more to the point, where the piece of meat smells fishy (cod is a species of fish).
In its original parlance, describing a thing or situation as "smells fishy" did refer to having probable cause for extreme doubt and suspicion, but most folks do not realize why innocuous fish are so maligned in this manner. A fishy or pungent-smelling discharge from the vagina or penis may signify the presence of an infection, so caution was advised...and still is today.
See the original glyph 韍: soft skin orifice between two feet, doggy style, as someone in need of knee protection whilst MAKING THE FULL CIRCUIT「screwing in spread legs」among the meat sacrifices offered for short-term rental by the shaman in her shrines and temples. Glyph similar to that of「meat markets, in the city」(市) and suggests the modern day practice of bar-hopping, trolling for _____ [fill in the blank with your favorite genitalia set], and so on…chafing the skin off a drunk's knees in the process until bloody, yet most males cannot perform more than a few times or more than a few minutes, unlike a trained female service provider who more than anything else under the circumstances might have appreciated some padding for her knees.
Original glyph of「knee pads. Sacrificial actions」(韍) uses elements of「softest skin orifice while doggy-style」and not too subtle: 巿 is suggesting that one「arrayed in one's loincloth」on the floor as knee protection prior to engaging the meat「screwing in spread legs.」…the need for knee protection may have been far more applicable to those service providers offering「soft skin orifices between feet」in sacrificial meat market actions all night long to the circuit of urban clientele who generally squatted behind the buttocks, and did not kneel. See Chinese erotic art for examples, and the glyph 韐.

External source definitions …excluding politically incorrect concepts and other meanings deemed offensive today; may include extended definitions, euphemisms, and mnemonics)
Chinese: see 韍
Unihan extended: revolve, make circuit, turn