If you are a member of or familiar with modern Western civilization, you are probably familiar with the witch, as well as the now-widely-accepted understanding that the entire concept is heavily based around the fear of (and desire to punitively control) women who refuse to hew to restrictive and sexist cultural norms. The whole notion of the witch riding the broomstick may, in fact, have had a basis in practices involving broomsticks covered in psychoactive substances (henbane, generally) which are then placed...well, in 'delicate places' of the woman's body in order to 'ride' the resulting high (Jordanes de Bergamo, "Quaestio de Strigis," approx 1470). This demonization of women ignoring their cultural norms to seek their own pleasure (and/or escape), even if apocryphal, wasn't an invention of the Western world.
In ancient China, women (especially in the northern part of China, Han society) were ruthlessly controlled. The practices of foot binding are a famous example intended to both demonstrate and actively enforce a woman's lack of independence. But what happened if there were women who refused to play along, and either from an excess of will and/or a fortunate place of birth made these opinions known? Women in southern China were not as systematically suppressed, and (it seems) naturally rumors of them being 'wild and deviant' sprang up in the north. As happened much later in Europe, a mythform arose to both stigmatize them and provide a rationale (excuse) for their punishment.
The practice of Gu (later named jincan) was the name given to one such practice. Gu (蛊) has been translated as a 'wug (蟲) inside a container.' I am not sure if the beaker container type also known as Gu is related, especially given the uncertainty of anglicized Chinese translations; however, the 'wug' (or Chong) was a catch-all term for a class of creatures which included snakes, bugs, and other amphibians and reptiles. The practice of Gu involved sealing a number of venomous small creatures - insects, snakes, toads and the like - into a container. They would then begin to consume each other, and the legend had it that their venom would combine in unpredictable ways, becoming stronger. This would eventually be used to poison unsuspecting men.
The effects of Gu poison on these men varied. In some cases it was said to 'confuse' them. Constance A. Cook states in her article "A Fatal Case of Gu Poisoning in Fourth-Century BC China?" that "By the Warring States era (c. 475-221 BC), it was understood as an affliction suffered by men who spend too much time with women and become 'confused' (kuo)" (Constance A. Cook, EASTM Journal 44 (2016): pp 123-149). She goes on to note that the condition was also linked with intestinal parasite infections, although whether that was linked to the folkloric preparation of the poison isn't made clear. Wikipedia notes that "Gu was used in black magic practices such as manipulating sexual partners, creating malignant diseases, and causing death."
However it was used and to whatever effect, the problem of Gu was such that by approximately 300 BC there was mention, in "The Rites of Zhou (周禮)", a book dedicated to Chinese (Confucian) bureaucracy and organization theory, of a 'Minister of Gu' - someone whose job entailed dealing with cases of Gu. It seems that this did not refer to the actual poison so much as to the practice or tradition which used it; I suppose the modern Western equivalent would be an inquisitor or witchfinder, although it was based squarely in the bureacracy of the government vs. in a purely religious organization (the tight links between government and religion of the time notwithstanding).
Does it work? Can one actually concentrate disparate venoms by having their producers consume each other? It seems unlikely. Toxic creatures tend to keep their venoms both concentrated and isolated within their bodies - not only for their own safety, but also because the normal metabolic processes would tend to destroy or degrade them (this is one difference, it seems, between a venom and a poison - poisons tend to enter the body through the alimentary canal although by no means exclusively, but their toxicity isn't generally degraded by this). Many venoms, lethal when introduced into the bloodstream, can be harmless or at least greatly diminished in effect if ingested by a healthy person as they cannot handle digestive chemistries or traverse the intestinal barrier. The body's reaction of vomiting is in part specifically meant to eject harmful substances that enter the body via the digestive system.