"Until the mid-1960s in Britain, pregnancy tests were done by sending a woman's urine to a lab, where it would be injected into a toad. The toad was checked two hours later and if it had laid eggs, the woman was pregnant."
[https://www.bbc.co.uk/news/uk-47815960]
Seriously, how did someone think of injecting all manner of urine into toads to see what happened?