Everything in the 19th century was disgusting, especially in England, and the city of Norwich (the second largest in the country) was having a particularly hard time with people peeing everywhere. Every dark corner (which was usually part of a church, adding a layer of blasphemy to the general grossness) was covered in the stain and stench of the urine of men who visited the city's popular marketplace, which -- like most places in the 19th century -- was sorely lacking in restroom facilities. The city imposed a fine on those caught with their pants down and ordered the owners of popular peeing spots to address the situation, but nobody wanted to build a urinal outside their business or church. Weird, right?
The people were on the verge of what would no doubt be a hilariously named riot, so property owners came up with a genius solution: designing sloping, convex structures into the corners of their buildings or wherever else a pee-er was likely to do their business.
The structures served two purposes: One, it forced prospective public urinators away from the corner, and they found that people who had to take their dicks out where everyone could see them were less likely to, well, do that. Even better, though, if someone was brave enough to give it a try anyway, their own pee was deflected back at them, soaking their pants and shoes and generally rendering the whole exercise pointless. Peehold the wonders of geometry, everyone.
The widespread installation of public bathrooms made the structures largely redundant at the end of the century, so most of them were removed. However, you can still see about 30 of them throughout the city, which really drives home the scale of the problem. Of course, people haven't stopped peeing in public, so versions of Norwich's anti-urinary devices are still in use in London. They're a bit more high-tech but even sneakier: a special coating painted on walls that repels liquid. You think you're peeing on a normal wall, but it sprays your own hubris right back at you. And you thought the British were masters of dry humor.
Manna, regrettably, has a Twitter.