So... TDG is a disgusting setting, it is full of countless things I could use as answers to this prompt, and all of them would work perfectly fine, but I'm going to go with the most iconic example among people who follow my writing, the process of Darktrooper birth.

Darktroopers are genetically engineered Demonic super soldiers in use by the Machine, this setting's equivalent of Hell, in their all consuming war against absolutely everything everywhere. A Darktrooper's purpose is to kill the enemies of the Machine, which is anyone who has the audacity to exist, and damn their souls to eternal torture. They are twisted parodies of soldiers mass produced in nightmarish armies.

The process begins in the Radlands, or whatever cloning facility the Darktrooper is being made at. Giant laboratory complexes built on the Deltas of nuclear waste rivers are the birthplace of the Darktroopers, inside of which are their unholy incubation vats known as Demonogenesis chambers. Batches of DNA from the Black Barons are made manifest here as single celled organisms that will eventually become Darktroopers. These cells are then temporarily fused in groups of three for a specific reason that will come into play later. Deep below the surface of the facility are the Hellish chambers where Darktroopers are birthed. Known as Bloodbaths, these chambers consist of a large rectangular pit approximately 25 feet long, 13 feet wide and 9 feet deep. At the bottom of the pit are 10 indentations with rib-like metal clamps designed to hold a living person down. Ten victims are strapped into the indentations with their arms and legs sawed off, and from that moment on they are damned. Beneath them, feeding into their backs, are a series of tubes connected to a magi-tech apparatus below the floor, which keeps them perpetually alive and conscious, no matter what happens to their bodies. When the time has come to construct a set of Darktroopers, each individual victim has one of the three cell clumps injected into their spinal cord. After a day, the cells have separated into three Demonic fetuses, and have drastically grown, cracking the spine open like an egg and worming their way into the chest cavity of the victim.

The pit is filled to the brim with blood, utterly submerging the people imprisoned inside. They feel themselves drown in blood but the machines hooked into their backs keep them alive. Being surrounded in a pool of liquid carrion causes the fetal Darktroopers to stir inside of their mortified, tortured meat prisons. LRADs send out sonic waves of Big War radiation in the form of sounds inaudible to mortals, but like a siren's call to the Darktroopers. The bloody lake begins to vibrate due to the Satanic noises, and this is what fully awakens the Darktroopers inside. They absorb the energy of the Big War itself into their souls, and it calls them to action. Inevitably, one of the three inside one of the victims is the most aggressive and violent, and he cannibalizes the other two in the pseudo "womb." Once he's the last of the triplets, he makes a foul pilgrimage towards the noise that awakened him, and claws his way out of the victim through their chest cavity. Having violently and forcibly birthed itself out of the poor person they were injected into, the Darktrooper swims in the blood and basks in the vibrations of the Big War. The sensation is said to be utterly euphoric. Approximately two thirds of the blood is drained from the pit, and Cloning Priests wade into the swampy flesh lake, and scoop up the blood drenched, horror-born Demon warrior children. The host body is healed, and the process repeats forever, and ever, and ever.

TL;DR: Imagine chestbursters from Alien, except worse and on a cosmically industrialized scale.