There’s a good reason that the right-wing group Patriot Prayer, which is holding a rally at Crissy Field in San Francisco on Saturday, better watch their step.

Leftist activists are planning to smear the field with dog poop.

Tuffy Tuffington, a 45-year-old artist and designer, created a Facebook event page to promulgate his idea of San Franciscans taking their dogs to Crissy Field for a stroll so the dogs could fertilize the field. He said he was walking his dogs when the idea struck him. He said, “I just had this image of alt-right people stomping around in the poop. It seemed like a little bit of civil disobedience where we didn’t have to engage with them face to face.”

Tuffington’s idea took off; some people excited by the idea responded by stating they would save their dogs’ poop for days, then bring bags of the excrement to the field. The group of volunteers is also planning to meet at the field on Sunday to “clean up the mess and hug each other.”

Other activists plan to confront Patriot Prayer by offering them flowers for their hair. Shannon Bolt, a behavior scientist who works at Crissy Field, told The Guardian that if security keeps the two groups apart, “We will have to offer our Flowers Against Fascism to them symbolically.”

Patriot Prayer has conducted free speech events in the Pacific Northwest. Despite the effort by House Minority leader Nancy Pelosi to label Patriot Prayer a white supremacist hate group, even the notoriously left-wing Southern Poverty Law Center (SPLC) reportedly does not consider Patriot Prayer to be a hate group. The SPLC reported that at a recent rally, its organizer, Joey Gibson, shouted from the stage, “F*** white supremacists! F*** neo-Nazis! ”

Gibson told Fox News that Saturday’s rally revolves around “a philosophy about promoting love and peace but doing it in a way that’s respectful. It’s about building bridges,” adding he wants to bring members of the radical Left group Antifa “out of the darkness.”