Perhaps stating so is overly obvious, but in many cases of sexual intercourse, on one side is an orifice of some sort that undergoes many lines of motion, and the other side has the skin, or prepuce: ONE-SIDED, A BIAS. A bias is a diagonal line from one corner to the opposite-angled corner, a SLANTED LINE, and in most cases the glans and prepuce shape cause a SLANTING shape during intercourse.
「Words, speak」with「skin」seems to have a weak connection at best to the given meanings, unless「speaking with skinned back skin」refers to the use of FLATTERY for the purpose of seduction. Relates to the English phrase「skin of one's teeth」since that idiom refers to one side being slightly ahead or succeeding when others do not. The English expression of「escaping by the skin of my teeth」makes no sense of course, but the original form of「escaping with my skin in her teeth」does indeed represent narrowly avoiding disaster of one's prepuce and surroundings during a session of「oral intercourse with the skin」as these elements depict. Anyone with a prepuce between her or his teeth certainly has a BIASED, ONE-SIDED ADVANTAGE over the person sporting that particular foreskin, and the unfortunate one being threatened would be wise to begin babbling FLATTERY.
「Talking about someone's foreskin」to them can only be FLATTERY, since it simply is not pretty. Left element literally as「tonguing motions in mouth」with「foreskin」produces the best fit with given meanings of UNFAIR, and ARGUE, causing an ARGUMENT and perhaps ONE-SIDED if we can assume some reciprocity is occurring simultaneously.「Speaking into or with a foreskin」will naturally become a ONE-SIDED conversation, and if the client has not paid for pleasant conversation but other services instead, may lead to an ARGUMENT, and particularly so if the charges are determined on a duration-of-time-lapsed basis rather than a fulfillment-of-performance basis, which would then be UNFAIR to the client.

External source definitions …excluding politically incorrect concepts and other meanings deemed offensive today; may include extended definitions, euphemisms, and mnemonics)
Chinese: unfair; to flatter
Japanese EDRDG: argue, biased, one-sided
Unihan extended: argue; biased; one-sided