「Head」with「thrusting downward」to mean PESTLE, held in a grinding bowl…see 臼 as the 'mortar for a pestle, cavity with two sets of lips, meat grinder.'
　Per scholars, represents MIDDAY, NOON as the middle of the daylight period when the Sun is at its ZENITH each day in its daily arc overhead…but may also represent the time of day when the older males were likely not around, and off in hunting parties, so that groups of females could do as they pleased.
　「…many people, unfortunately, feel shame around masturbation, despite the fact that 98% of people will masturbate at some point.」
　　[　https://www.health.com/mind-body/health-diversity-inclusion/autosexual-meaning 2022-12-13　]　
　This is also the ancient glyph for HORSE used in the Zodiac to denote this two-hour period, perhaps because horses stand to an extreme, standing and running on one toenail of each foot on each leg, and even sleeping in a standing position by locking all four knees, unless they feel absolutely safe from predators, then they might lay down, but in the wild a horse sleeps standing.
　As「head of downward thrusting penis」the glyph plainly refers to a DILDO when used as an element, such as grinding within a cavity with two sets of lips (臿). As one defining characteristic, HORSES naturally perform an 'array of talented tense prick bouncing for emissions' on a regular basis, masturbating on average about every hour and a half when in the wild:
　「Sue M. McDonnell, PhD, is an equine behaviorist on a mission -- to inform and educate horse owners and handlers that stallion masturbation is normal, healthy behavior and that trying to discourage such behavior is likely to do more harm than good. McDonnell holds a PhD in reproductive physiology and behavior, and she is the director of the Reproductive Behavior Program at the University of Pennsylvania's New Bolton Center. McDonnell and her research team have conducted several studies pertaining to masturbation in equids, and after years of research and investigation, McDonnell concluded that stallion masturbation is normal, healthy behavior in equids -- and perhaps even necessary for healthy sexual function.」
　　[　https://ia802906.us.archive.org/0/items/largeanimalinternalmedicine/16-%20Understanding%20Horse%20Behavior.pdf 2023-05-17　]　
　Female horses, the mares, also masturbate regularly during estrus, at which time they become really friendly with trees, fence boards, anything else they can back into and rub against.
　「Evolutionary biologists have traced the origins of masturbation to ancient primates that predate the first humans by tens of millions of years. The findings emerged from what scientists believe is the largest dataset ever compiled on the activity, and confirm that humans arose on a branch of the tree of life replete with self-pleasuring predecessors. 'What we can say is this behaviour was present around 40m (40,000,000) years ago, in the common ancestor of all monkeys and apes,' said Dr Matilda Brindle, the lead researcher on the study at University College London. 'It's not that some species woke up one day and started doing it. This is an ancient, evolved trait.' '…This is such a common behaviour across the animal kingdom, I find it absolutely baffling that nobody has researched it before,' said Brindle. 'For people who think masturbation is wrong, or unnatural in some way, this is perfectly natural behaviour. It's part of our healthy repertoire of sexual behaviours.'」
　　[　https://www.theguardian.com/science/2023/jun/07/origins-masturbation-traced-back-primates-40m-years-ago　]　
　「The head with bougie reaming and twisting, screwing」was a medical procedure not performed at night, for safety and other good reasons, performed with the patient lying flat on his back and that other head and neck straightened, pointing toward heaven.
　(1) 子 rat (children, spermatozoa)
　(2) 丑 cattle (herded meat assets, harem)
　(3) 寅 tiger (religious dogma, enslavement)
　(4) 卯 rabbit (female, reproduction)
　(5) 辰 dragon (power sex)
　(6) 巳 snake (fornication)
　(7) 午 horse (autoeroticism)
　(8) 未 sheep (zooerastia)
　(9) 申 monkey (deities, anal-centric)
　(10) 酉 cock (cognitive processing impairment)
　(11) 戌 dog (male, domination)
　(12) 亥 swine (humanity in general).
　Without a doubt, the Irish also have knowledge of their own to pass along in these trying times:「Masturbation will not spread coronavirus, especially if you wash your hands (and any sex toys) with soap and water for at least 20 seconds before and after.」Nonetheless and regrettably, unlike in dynastic China, it must be undertaken alone to truly be a preventative countermeasure but still achieve the desired result with some degree of safety.
　 　[　https://www.sexualwellbeing.ie/sexual-health/sex-and-coronavirus/ 2020-03-31　]　
　The Dutch, too have the same solution—it seems masturbation has become mainstream in the media the world over due to the coronavirus (it has always been 'the main stream' in reality, albeit covertly for most folks):
　「'Don't have sex with your partner if they have been isolated because of (suspected) coronavirus infection,' the RVIM says. 'Sex with yourself or with others at a distance is possible (think of telling erotic stories, masturbating together).'」
　　[　https://www.theguardian.com/world/2020/may/15/dutch-official-advice-to-single-people-find-a-sex-buddy-for-lockdown-coronavirus 2020-05-16　]　
　Needless to point out perhaps, but Chinese shamans from antiquity hit upon the same solution as a pandemic preventative countermeasure, honed for ultimate client satisfaction by utilizing naked females with no-longer-integrated feet as masturbatory sex buddies available for short-term rental with erotic visualization of live prepubescent female genitalia engaging in autoerotic stimulation herself, as a solution to the same problem facing us now, but in pre-Internet days.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: 7th earthly branch: 11 a.m.-1 p.m., noon, 5th solar month (6th June-6th July), year of the Horse
Japanese: seventh sign of Chinese zodiac, noon, midday, just past noon, afternoon
Unihan extended: noon; 7th terrestrial branch
EDRDG: noon; sign of the horse; 11AM-1PM; seventh sign of Chinese zodiac