Tyler made a quizzical expression, then turned to look at his friend.
"The stock market is at record highs," Trump said. "Unemployment is at record lows."
Tyler raised his eyebrows and chewed his lip.
"And more Americans are working today than ever, ever, ever before!" Trump stated.
Tyler glanced upward and appeared to mouth: "Is that true?"
His facial expressions soon caught the attention of his friends, who had been watching the rally on TV and texted Tyler to say he was, um, extremely visible. It was around that point that Tyler took a "Democratic Socialists of America" sticker from his pocket and affixed it to his shirt, he said.
Tyler's friends weren't the only ones who noticed his face. Scores of other people watching the rally on television were quick to zero in on Tyler's divergent reactions to Trump's speech, like a real-time game of Where's Waldo meets "One of these things is not like the others." On social media, "the guy in the plaid shirt" quickly translated to #PlaidShirtGuy - and a meme was born.
Tyler said it was never his intent to troll Trump. Though he is not a Trump fan, per se, he had planned to attend the rally when he heard Trump would be visiting Montana because he didn't want to miss an opportunity to see the president.
The day of the rally, Tyler was notified that he had been chosen at random for "VIP status," meaning he would get to meet Trump for a photo-op, he told The Washington Post.
"Before I got the picture and the handshake with Donald Trump, I asked him if me and my friends could sit behind him," he said. "I had no idea I was going to be on Trump's shoulder. I didn't know it was going to be so zoomed in right on me and my friends. I didn't know it was going to be like that all."
Everyone behind Trump was told to cheer and look as energised as possible. Tyler said his reactions - or his stone-faced lack of reaction while others were applauding - were simply him keeping it "real." He clapped when Trump said Bernie Sanders had had the Democratic nomination stolen from him. Though Tyler was too young to vote in the 2016 presidential election, he had been a big supporter of the senator from Vermont.
More often than not, though, Trump said things Tyler disagreed with.
"Whenever we thought he said something completely outrageous, we would look at each other and say, like, 'Did he really just say that?' Did that really just happen?' " he said. "I wasn't planning on trolling him or protesting. When I heard something that I disagreed with, I visibly disagreed. I had to be real with myself. I'm not going to pretend to support something I don't support."
It took Trump's campaign team a while to zero in on Tyler and his friends, but sure enough, a woman in a black dress eventually could be seen walking up to Tyler onstage and taking his place. Shortly afterward, his two friends were also removed.
"I just saw her coming on my left, and all I heard her say was, 'I'm going to replace you now,' " he said. "I knew I was getting removed because I wasn't enthusiastic enough. I didn't try to resist, so I just left."
The Trump campaign did not return a request for comment Saturday morning.
The teen said some Secret Service members and local police escorted him to an area at the edge of the auditorium, where they asked for his ID and held him for about 10 minutes. They then "in a nice way asked me to leave and not return," Tyler said.
"I'm not sure what they would have done if I didn't leave," he said. "I didn't want to make a scene more than I already did."
Tyler knew he had gone viral after he bumped into some friends outside the arena and they told him: You're trending. And boy, was he. The Billlings Gazette tracked him down and identified him as a senior at Billings West. The Daily Beast described Tyler's facial expressions as "Jim Halpert-like." He was interviewed on local news and invited to appear on "CNN Tonight" with Don Lemon, still clad in the same plaid shirt.
Tyler said he expects the hubbub to fade soon.
"Things on the internet die quickly," he said.
He's more excited to finally turn 18 next month - in time to be able to vote in the upcoming midterm elections.
"Um, I don't know when it started," Tyler said of his interest in politics. "I've always just liked being informed. I like knowing what's going on."
He had, in fact, attended a rally with Vice President Mike Pence the month before, also in Billings, with little fanfare.
"I don't want to miss out on these opportunities," Tyler said. "That was pretty different. There was no one sitting behind Mike Pence at that rally, so I got there really early and I sat in the front row. I was doing the same thing. I wasn't clapping [when I disagreed with things he said]. When I did agree, I would clap."
He paused when asked to consider if he had reacted as nakedly to Pence's speech as he had Thursday.
"I was probably making faces, too," he said. "I don't have a poker face at all."
