In their efforts to drive political opponents from the public square, self-described “anti-fascists” (or “antifa”) are utilizing a disgusting and degrading weapon: human urine.

In just the latest instance of weaponized urine, counter-protesters demonstrating against a free speech rally in Boston on Saturday flung urine-filled bottles at police officers trying to maintain order amidst an already tense political climate.

The Boston Police Department sent out a message on Twitter urging demonstrators not to assault officers with urine, but it’s unclear if it had any effect. Boston Police Commissioner William Evans stated at a press conference later that day that protesters successfully hit officers with their urine-filled projectiles.

“I’m sorry to report that we did have some bottles thrown at our officers that did have urine in it. A couple of our officers were hit with that,” Evans said. “They were hit with a lot of stuff today.”

#BPD is asking individuals to refrain from throwing urine, bottles and other harmful projectiles at our officers. — Boston Police Dept. (@bostonpolice) August 19, 2017

The use of urine appears to be a trademark tactic of self-described “anti-fascist” demonstrators.

Antifa brought urine-filled projectiles to the violent clashes between white nationalists and antifa in Charlottesville, Virginia earlier this month. Journalists were among those hit with urine.

“Two of my producers just got sprayed with urine,” journalist Katie Couric wrote on Twitter. “Lovely. Hard to keep your cool.”

Couric didn’t name which side the pee culprits were on, but reporters with The Daily Caller News Foundation witnessed far-left demonstrators launching urine-filled balloons at white nationalists.

As this past weekend’s events in Boston showed, it’s not just suspected white nationalists who get hit with urine.

Left-wing counter-protesters at a June 4 free speech rally in Portland, Oregon launched balloons filled with human urine and feces at the free speech rally-goers, the city police chief recounted in a letter to Portland’s mayor.

“The decision to move the group located in Chapman Square was made after [Portland police] had repeatedly observed objects being thrown and shot from slingshot type devices from Chapman Square into Terry Shrunk Plaza,” Chief of Police Michael Marshman wrote. (He noted earlier in the letter that Chapman Square was “the site of one of the counter protests,” while Terry Shrunk Plaza was the location of the free speech rally.)

“These objects included urine and feces filled balloons, balloons with unknown chemicals, marbles, bricks and rocks,” Marshman wrote.

Local news coverage described the urine-flinging counter-protesters as antifa members. (RELATED: Leader Of Portland Anti-Trump Protests Charged With Sexually Abusing Minor)

Right-wing YouTuber and activist Lauren Southern says she’s been doused with urine by antifa on multiple occasions, including one occasion where she says the bottle was labeled as fox urine.

Popular antifa website It’s Going Down confirmed that “anti-fascists” have hit Southern with some form of urine at least once.

An article posted on the website in April stated that “anti-fascists threw urine on her when she came out to defend an American Front meeting that was happening.” (RELATED: In Their Own Words: The Radical Political Goals Of ‘Anti-Fascists’)

Right-wing provocateur Milo Yiannopoulos said attendees at a speech he was going to give at the University of California, Davis in January were also hit with urine.

After protesters forced the speech’s cancellation due to safety concerns, Yiannopoulos wrote on Facebook that “guests were sprayed with urine and had bags of feces thrown at them” by “left-wing thugs.”

The university stated that police were unable to confirm that protesters were throwing urine and feces at attendees although multiple news outlets reported guests saying that urine was, indeed, thrown at them.