Determined to prove that yellow fever is not contagious trainee doctor Stubbins Ffirth (yes, that is his real name) demonstrated that no matter how much he was exposed to the disease, he would not catch it.

He poured 'fresh black vomit' from a patient into deep cuts on his body, his eyes and even built a 'vomit sauna' filled with vomit vapour. He drank it too (it's called 'black vomit' due to the darkly haemorrhaged blood in the stomach).

Healthy as a horse he declared his hypothesis proven in his 1804 thesis. Here endeth the lesson!