The 42 year-old home owner in Duisburg, western Germany, caught sight of somebody urinating in his front garden on Tuesday and went outside to ask him to stop.
After a brief verbal argument, the drunken micturator pulled out a gas pistol and shot the man in the face, the Westdeutsche Allgemeine Zeitung (WAZ) reported.
The pistol had released so much tear gas that when the victim's 38 year-old wife hurried out to see what was going on, she also suffered inflammation to her eyes.
The married couple had to be taken to hospital to receive treatment for their injuries.
"When you come into contact with tear gas, you understand the meaning of pain," said police spokesman Joachim Wawrzeniewski
The doctors estimated that the gas must have been shot from a distance of two or three meters.
After shooting the man point in the face from point blank range, the drunken culprit fled the scene.
According to local police, he was blonde and was wearing a double-denim jeans-jacket combo, but neither the victim nor his wife could give an estimate regarding his age.
A tear gas pistol might not seem like a key ingredient for a night on the town, but adults are permitted to carry one by law in Germany.
As long as you have a small weapons permit, have registered the pistol with the police, and passed a number of tests, it is perfectly legal to carry one on your person.
But unsurprisingly, "it is illegal to shoot another member of the public with it," said the police spokesman.
A public urination epidemic?
Lots of German cities are attempting to crack down on public urination with enormous fines for those caught in the act.
Here is a map showing how the possible punishments for relieving oneself on the go vary across the country:
Berlin's unofficial motto may be "poor but sexy", but the capital doesn't seem too concerned about the smell of wee ruining the city's sexiness, with the lowest fine in Germany at only €20.
But other cities like Hannover, Stuttgart, Kaiserslautern, Erfurt and Halle seem much more determined to keep their streets in pristine condition, with fines going up to €5,000.
Peeing in the street is most common during big public events, as the deadly mix of copious amounts of alcohol and long queues for portaloos can tempt the most law-abiding citizen to find an opportune spot to relieve themselves.
Various cities raise the fines for special events, like in Cologne and other cities in the Rhineland during Carnival and Fasching, and in Munich during Oktoberfest.
St. Pauli, an area of Hamburg, has got creative in fighting the problem with the slogan "Don't pee here, we pee back".
A local interest group has covered opportune peeing spots in the area with liquid repellant paint so that public urinators will suffer splash back.
"Public urination is a public offense and will be punished. By doing so people are disturbing the general public," says Swen Walentowski, spokesman for the German Lawyers Magazine.
The legal situation is clear, but the punishment can vary hugely.
The level of the fine also depends on the location.
Urinating in parks or wooded areas will usually land you with a smaller fine, but doing so up against the wall of someone's house in the open street could hit the wallet hard.
By Matty Edwards