Disclaimer: This visuals in this clip may be discomforting.
In this visualization of 18th century medicine, Abigail Adams and her children get inoculated against small pox. Innoculation was pioneered in the West by Edward Jenner.
The group takes a boat ride through the small intestine, where the workers are not only singing about the intestine but are also part of an assembly line that illustrates the small intestine's function: the digestion and absorption of food.
While in the middle of its boat ride, the group encounters the sexually transmitted infection, gonorrhea. Before destroying gonorrhea with a lit match, Poncho alludes to a symptom of the infection: a burning sensation during urination.