After inviting a fan on stage, Urista instructed him to lie down. She then proceeded to pull down her trousers and appeared to urinate on his face, while still performing the song.
Those at the show in Daytona Beach, Florida, and people watching the clips online branded the moment “disgusting”.
The New York-based collective has since apologised for the stunt and said Urista got “carried away”.
“We had a great time last night at Welcome to Rockville,” they said in a post on Twitter.
“Sophia got carried away. That’s not something the rest of us expected, and it’s not something you’ll see again at our shows. Thanks for bringing it last night, Daytona.”
We had a great time last night at Welcome to Rockville. Sophia got carried away. That's not something the rest of us expected, and it's not something you'll see again at our shows. Thanks for bringing it last night, Daytona.
— Brass Against (@BrassAgainst) November 13, 2021
The band’s Facebook page, which has more than 450,000 fans, describes them as “a collective with the goal of creating music to inspire social and personal change”.
Before the incident, Urista was heard telling the crowd that she needed to urinate. “Get my man with the can on his head ready, ’cause we’re going to bring him onstage and I’ma p*** in this motherf***er’s mouth,” she said.
“I gotta pee,” she added. “And I can’t make it to the bathroom. So we might as well make a show out of it.”