「Old meat」that was not new, not fresh, not young prepubescent meat (with no pubic hairs yet grown). Old meat is hairy…so this glyph means BEARD, MUSTACHE, WHISKERS that are all examples of PUBIC HAIR growing on a physically mature male…perhaps「meat the old fashioned way」as in unshaven, covered with natural hair growth. Most carnivorous-omnivorous animals, other than humans, eat meat raw with skin and hair still attached: HAIRY MEAT THE OLD FASHIONED WAY, BARBARIC.
Meat that appears old but may not actually be aged is on a person who has not taken good care of his or her health, instead living a wild and RECKLESS, OUTRAGEOUS lifestyle.
WHAT? WHY? as an exclamation of wonderment, after learning that anyone would select that sort of「old meat」as a BLUNDER. Perhaps「screwing orifice, old」with「meat, erection in no-longer-integrated feet」as a BLUNDER. Perhaps BARBARIAN FOREIGNERS did it「the old-fashioned way with their meat」by simply screwing the natural orifice only while foregoing no-longer-integrated feet.
Chinese thinking of BARBARIAN FOREIGNERS as OUTRAGEOUS, which means「grossly offensive to decency or morality, being well beyond the bounds of good taste, having no regard for morality, violent or unrestrained in temperament or behavior [rage, anger], extremely unusual or unconventional, being beyond all reason, extravagant or immoderate」
[ https://www.thefreedictionary.com/Outrageous ]
Perhaps refers to the shriveled and shrunken shape of an old man's genitals (「meat」) or diseased, enlarged prostate gland (「old」) that became so from the BLUNDER of not continually using the body's seminal pumping system to ejaculate. Glyph is also used to represent「walnut meat」the edible part within the shell, probably due to the resemblance of walnut meat and shells to diseased prostate glands and an old man's scrotum, respectively.
Ingesting「meat」that was「old」might make you ill and be a BLUNDER. Refers to BARBARIANS FROM THE NORTH or WEST (the southern barbarians were「dogs」) as WILD, RECKLESS, VIOLENT BERSERKERS. Glyph is also used to describe dried sesame seed pods, cucumbers, walnuts, fava bean pods, etc., that strongly resemble a plant full of human penile erections and/ or scrotums, albeit a bit shrunken as if from「old men's meat」(Asian cucumbers are much thinner but with many more skin bumps than those in the West…).

External source definitions …excluding politically incorrect concepts and other meanings deemed offensive today; may include extended definitions, euphemisms, and mnemonics)
Chinese: beard; mustache; whiskers; see 衚衕|胡同; non-Han people, esp. from central Asia; reckless; outrageous; what?; why?; to complete a winning hand at mahjong (also written 和 )
Japanese EDRDG: barbarian, foreign
Unihan extended: recklessly, foolishly; wildly

Used within names (nanori)
えびす　･　くる