「Snake」「surrounding from above, deliberately out-of-reach」with a「fallen person」: anciently it seems that snakes and insects were thought of in the same vein. Right element of a fallen person under a roof of a pit hole home suggests being bitten by a VENOMOUS SNAKE, VIPER, ASP that was in the pit along with you, and seems to refer to「some other」animal in the pit with you that has set you on your buttocks, such as a venomous snake. Note that a scorpion sting will normally not knock you out as does snake venom unless you are especially allergic to it. The venom initially deployed by a scorpion in defense is painful, but not nearly as toxic as its other variety, used to kill bugs (scorpions have two types of venom).
　Snakes and other reptiles have「branching, skilled glans」(岐) and concubines in China had two no-longer-integrated feet that were wrapped around a rod and then squeezed in a constricting manner (however, note that constricting snakes are not generally venomous). Comparison of「vulva, rod within orifice, both sides」「loose and dripping, snake, larva, worm, insect」「it, that other thing, out-of-reach sitting person with no-longer-integrated feet」with a VENOMOUS SNAKE, VIPER, ASP as referring to both the client(s) and the service provider is apparent:「A hemipenis (plural hemipenes) is one of a pair of intromittent organs of male squamates (snakes, lizards and worm lizards). Hemipenes are usually held inverted, within the body, and are everted for reproduction via erectile tissue, much like that in the human penis. Only one is used at a time, and evidence indicates males alternate use between copulations as a behavioral means of increasing sperm transfer when the interval between copulations is relatively brief. The hemipenis itself has a variety of shapes, depending on species. Often, the hemipenis bears spines or hooks, in order to anchor the male within the female. Some species even have forked hemipenes (each hemipenis has two tips).」
　　[　https://en.wikipedia.org/wiki/Hemipenis 2014-06-23　]　

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: snake; serpent
Japanese: snake, serpent, large snake, false strawberry, mock strawberry
Unihan extended: snake
EDRDG: snake; serpent; hard drinker

Used within names (nanori)
あぶ　･　み