When you work your way down to the lowest form of humor, you reach the scatological…
Wikipedia has a great description of it under the other appropriate heading: “Toilet Humor”.
And of course, A Game of Porcelain Thrones is ALL about toilet humor.
If it’s good enough for Chaucer, it’s good enough for me!
From Wikipedia:
Toilet humour or scatological humour is a type of off-colour humour dealing with defecation, urination and flatulence, and to a lesser extent vomiting and other body functions. It sees substantial crossover with sexual humour, such as dick jokes. The term scatology is derived from the word ‘scat’ often interchanged with ‘feces’ particularly when referring to droppings of prey animals while hunting. (i.e.bear-scat) From the Greek skor, skat.