Throughout history, rulers and despots all over the world have sought to impose levies on all kinds of unlikely things.

Hearths, windows, candles, and even soap have all been taxed at some time or another in England, as have playing cards, the ornate design of the ace of spades developing from the official insignias of printing houses, used to prove that the requisite duties had been paid. For centuries before the French revolution, salt was taxed in France. One of the oldest taxes we know of was a tax on cooking oil imposed by the pharaohs of Ancient Egypt more than 5,000 years ago. And in 1698, in a vain attempt to modernize his country, the Russian leader Peter the Great famously imposed a tax on any man wanting to sport a beard; the tax remained in place for the next 74 years.

But of all of history’s most unusual taxes, perhaps the strangest—and easily the most unpleasant, was that imposed by the Roman emperor Vespasian in 70 CE.

As bizarre as it sounds, in Ancient Rome, human urine was a major commodity. The ammonia that could be extracted from it was used to bleach and clean the pristine white togas worn by Roman statesmen and noblemen, while urine could also be used in the production of wool and the tanning of leather, skins, and animal hides.

A tax on the collection and disposal of urine was first imposed on Rome in the 1st century CE, under Emperor Nero. Those who wished to purchase the urine collected in Rome’s communal latrines were ultimately required to pay a tax on the quantity they bought. But Nero’s original urine tax quickly proved unpopular and difficult to keep track of, and so was promptly repealed. When he died in 68 CE, the brief period of turmoil that followed, known as “The Year of the Four Emperors”, quickly strained the city’s coffers, so that when Vespasian finally took to the Roman throne in December 69 CE, the Roman state was perilously close to bankruptcy. Consequently, Vespasian felt compelled to reintroduce his predecessor’s bizarre and unpopular tax, and Nero’s urine-collecting levy was doled out once more on the people (and toilets) of Rome.

Happily, the tax later went on to be repealed for a second time, but not before it had two left two somewhat bizarre and lasting impacts on our language.

French urinals still to this day are known as vespasiennes in Emperor Vespasian’s honor, the name being chosen as a euphemism in the early 1800s when a network of public restrooms was first opened across Paris. Meanwhile, according to the Roman historian Suetonius, when Vespasian’s son Titus first heard about his father’s urine tax, he expressed disgust that his father was trading and dealing in the purchase of urine. In response, Vespasian is said to have held up a gold coin in front of Titus’ face and asked him if he thought it smelled. When Titus replied that it did not, Vespasian responded, “ah, and yet it comes from urine!” Suetonius’ bizarre anecdote went on to inspire a famous Latin motto, pecunia non olet! —literally, “money does not stink!”, which remains in use today as a reminder that it doesn’t matter how you make money because it all has the same value.