"No Trump! No KKK! No fascist USA!"

Tuesday night, thousands of protesters yelled at Donald Trump's supporters as they trickled into the convention center across the street. It seemed like every other protester held a sign, flag or banner decrying bigotry, celebrating love, condemning Nazi scumbags or comparing Trump to Klansmen and dictators and pigs.

"No Trump! No KKK! No fascist USA!"

They chanted past two rows of metal barriers and a line of armed police officers dressed head-to-toe in heavy, black riot gear. They must have been sweltering. The sky had been clear for days, letting the summer sun scorch the streets of downtown Phoenix until the asphalt shimmered with imprisoned heat. By the time protesters had gathered on Monroe Street, pressing themselves against those metal barriers and filling every open space of the adjacent three-story parking lot, the sun was setting. But it still hit 108°F that day and Phoenix hadn't seen a monsoon in over a week. The air was thick.

On the protesters' side, the vibe was focused, tense and sweaty. People smiled, laughed, offered each other water, posed for selfies and -- most importantly -- heckled every new Trump supporter that emerged across the street.

"Racist! Racist! Racist!" they screamed. Across the barriers and police officers and summer-hot asphalt, people going to the Trump rally grinned and waved, or flipped off the crowd, or yelled back, or filmed all of it on their smartphones without saying a word.

"Racist! Racist! Racist!"

A handful of people looked around at this chant, not joining in. From somewhere in the crowd, a woman started a new rallying cry: "They go low, we go high! They go low, we go high!" It picked up steam. The anxious energy in the mob abated, redirected once more to its true target across the street, just beyond the cops' riot gear.

Don't feed the trolls. Instead, accuse them of hate crimes through a megaphone with an army of thousands at your back, amplifying your attack. It feels contradictory to preach one method of resistance online and its opposite in the physical world; a sort of cyber-reality cognitive dissonance. But, these two pieces of advice -- stand down and stand up -- aren't inherently opposed. They simply address different problems.

Online, it's wise to not feed the trolls when you're the one being sought out, harassed, targeted. Don't play their games, don't give them the satisfaction, don't engage lest you accidentally breathe new life into their threats. "Don't feed the trolls" is a defensive measure.

Protesting is offline offense. Protesting is a strategic response to a cataclysmic event, something so shocking or vile that it infuses people with a burning desire to do something more than sending a tweet. It's a method of effecting policy change, starting a conversation, or just screaming out your frustrations with the world. Sometimes, it's all of these things.

Pressing send on a string of tweets about how awful Nazis are can add volume to the online conversation, but more often than not, sharing common outrage on social media feels like shouting into the ether. Attention shifts in an instant online, and by the time you've crafted the perfect response to a national crisis, it seems like 50,000 people have beaten you to it. Or worse, they've said it better.

Protesters, on the other hand, shout at the monsters that caused their disgust, rather than screaming at their friends and loved ones. Plus, every body on the ground makes the movement bigger, the message stronger. Each person matters, even those with just five Instagram followers. Protests are a chance to truly feel like something bigger.

Rallies serve the same purpose.

But protests are inherently against something -- usually an idea, sometimes a person -- which places attendees in a delicate situation. It's too easy to immediately assume everyone around you is good and right, and everyone on the outside is bad and wrong. It's too easy to blindly scream, "Fascist!" at the strangers across the street before realizing, Wait, is that Aunt Jodie?

Essentially, it's too easy to become something that looks a lot like a troll. To the police officers, that's exactly how it looks.

The question that keeps protests from devolving into unproductive, irate mobs is usually, "What do we stand for?" This is the question one woman answered in Phoenix on Tuesday night when she changed the chant from, "Racist! Racist!" to, "They go low, we go high!" It's the question answered by every chant and sign that night about justice, equality or Black Lives Matter -- a movement that found its momentum online (largely on Twitter) but that does work in the real world.

There's no chapter called "Don't feed the trolls" in the police officer's handbook.

In Phoenix, the police didn't use tear gas on the crowd until Trump's speech wrapped up. Minutes after his rally ended, the police force in front of the convention center swelled. The crowd behind the barriers grew as rally-goers began to leave the building and protesters prepared to chant again. From the back of the group, someone threw a water bottle at the line of officers.

Protesters watched it fly with a sense of dread, immediately searching for the culprit, hoping to shut them down. Another water bottle soared over the heads of protesters, nearly hitting an officer across the street. Behind the giant black Antifa banners staring down the cops -- "Death to Fascists" -- the crowd parted and collapsed on itself. A fight.

BANG. Tear gas filled the air, stinging lips and tongues and eyes.

BANG. The protesters fled. BANG. The people throwing water bottles and rocks, causing problems and inciting violence -- the trolls -- fled.

Their eyes red and welling in the yellow mist, everyone looked the same. Except the police officers, wearing helmets, carrying shields, and feeding pepper spray to the crowd.

Images: Jessica Conditt / Engadget