PopMob is not enjoying its 15 minutes of milkshake fame.

The antifascist organizers known as Popular Mobilization, or PopMob, sent a letter July 15 demanding the Portland Police Bureau retract and correct a tweet on June 29 that suggested protesters mixed quick-drying cement into vegan milkshakes.

"The city's irresponsible statement has resulted in many death threats and other violent communications being directed at PopMob organizers," says the letter, first reported by The Portland Mercury.

The only evidence Portland police had of the concrete milkshakes before sending the tweet was social media rumors and observations by Lt. Rick Stainbrook, who told other officers he saw a powdery substance on a milkshake cup and thought the frozen concoction smelled like cement.

PopMob says its organizers used cashew milk, coconut ice cream and rainbow sprinkles to make the milkshakes.

The Police Bureau did not respond to a request for comment on the antifascists' demand.