Summary by Wrathkal
There's a Marisa-Reimu couple awaiting the birth of their children, when suddenly their children on the stalk start screaming and excreting, to the consternation of their parents. Turning black, emitting paste from every orifice, etc, before they fall off and die even as their parents keep yelling at them to take it easy.
Just as they're asking why, the parents start vibrating as though they're refreshing, with their words stuttering and stretched out. Their eyes spin, they pee and poop themselves, and lastly, paste explodes out through their orifices, and they die.
This is the effect of the Factory's recently released item 'Yukkuri Speaker', an extermination tool that attacks the paste core directly.