CLEVELAND — It’s hard to go anywhere in this city without seeing a “Party at Napoli’s” T-shirt. They were at Game 1 of the World Series. They were in Indians’ clubhouse. Dudes in the local bars are walking around in them.

Heck, even Mike Napoli himself, Cleveland’s slugging party machine, was wearing one at World Series Media Day.

“There’s the postseason shirt,” says Nate Crowe, a 38-year-old father of three, sitting down with a plate of tacos in front of him at restaurant across from Progressive Field, pointing to a guy walking past. Crowe has been an Indians fan all his life and carries along with his fandom a certain affinity for DIY signs and T-shirts.

That’s how, on one day back in April, Crowe bought a tri-fold poster board from Target for $8.99, grabbed some double-thick markers and made a sign that said “Party at Napoli’s.” He stood in right field at Progressive Field and held it up, trying to get the attention of Indians’ players. He got a whole lot more than that.

What followed was a social media campaign, a T-shirt, a six-figure charity effort and now the rallying call that has brought the Indians all the way to the World Series, where they have a 1-0 lead after shutting out the Cubs in Game 1.

“I figured it was all an inside joke and it would disappear,” said Crowe, who works in purchasing for a Fortune 500 company and whose alter ego on Twitter is @HipsterTito.

It happens all the time in our meme-centered culture. A thing pops up and it’s all the rage for two weeks. It trends on the Internet. Some T-shirts are made. Then the next thing comes along. Doesn’t matter if it’s sports, pop culture or life in general. But “Party at Napoli’s” is different.

The whole thing started when the Mariners were in town. Crowe, a season-ticket holder, usually hangs out with a dozen or so other diehard Indians fans in the standing-room-only section in right field. They have fun and bring signs and heckle the opposing team.

On this night, making fun of Seth Smith didn’t seem too appealing, so Crowe decided to make some signs instead. He had a few of them, all inside jokes that more plugged-in Indians would get. Party at Napoli’s was a nod to the 2013 World Series, when Napoli won with the Boston Red Sox then celebrated shirtless in the bars and streets of Boston.

“We’ll bring a sign that will get some attention and I’ll make it big enough that they can read it from the dugout,” he recalls. “I would hold it up whenever they went out on the field or during warm-ups. I had a friend take a video and put it on Twitter and people started to respond.”

People loved it immediately. They came and took pictures and shared them online. His $8.99 was getting put to good use. But soon enough, he took things a step further by making his own “Party at Napoli’s” T-shirt. It required an $7 T-shirt and $28 worth of iron-on letters.

“I made it, I looked at it and thought, it would be kinda cool if Mike had one too,” Crowe says. “My wife comes home and says, ‘What are you doing?’ I’m making a shirt for a baseball player I don’t know. Yeah, this does look kinda sad, just go with me.”

He was looking for a couple of laughs, for a connection with his baseball favorite team. Then, in June, Napoli hit a walk-off sac fly and wore Crowe’s handmade T-shirt in a TV interview. Crowe saw it on TV that night and he ran upstairs and woke up his wife. His $35 handmade shirt had made it.

Crowe had become friendly over the years with the people who run the Indians Twitter account and asked them to give the shirt to Napoli. It took a while, but he finally wore it. And the party hasn’t stopped since then.

After that TV interview, Crowe got a message from an Indians employee: “I guess we’re going to want to make some shirts.” Fans, especially on Twitter, had already adopted #PartyAtNapolis as a go-to hashtag for whenever he or the Indians did well. But things went to another level when Mike Napoli himself embraced it.

“I like to have fun,” Napoli said this week, when asked why the “Party at Napoli’s” idea resonated so much. “I have a fun personality.”

He has a good heart too. It was Napoli’s idea to turn the T-shirts into a charitable endeavor.

“I don’t want any money,” Napoli said. “But let’s try to spin it off into getting some money for charity.”

So next came official T-shirts, made by MLB partner 108 Stitches, with the proceeds going to Cleveland Clinic Children’s. When Crowe was asked what cut he wanted in the sales, he followed Napoli’s lead. The children’s hospital was a cause close his heart.

More than a decade ago, his first child was born two and a half months premature and spent two months in the hospital. They used money from a second mortgage to pay the bills. He also asked that some money go toward a cancer charity, since his father was recently diagnosed with a chronic form of leukemia and 108 Stitches is the company that makes the “K Cancer” T-shirts with MLB.

So far, more than 13,000 “Party at Napoli’s” T-shirts have been sold at $32 each with more than $200,000 going to charity. There’s a postseason version now. There would likely be another if the Indians win the World Series. All from a sign made on a whim by a baseball fan.

That’s only half the story, though. When Crowe got to spend some time with the Indians, pitcher Trevor Bauer came up to him and said, “That’s going to be our slogan when we win the World Series. We’re all going to have the Party at Napoli’s shirts on.”

The first part has happened. And the rest very well could.

“It was enough of a hit that the fans ran with it,” Bauer said this week. “If the fans are talking about it, tweeting about it, that keeps the enthusiasm going.”

Maybe it’s a testament to Cleveland as a place where fans can still have meaningful interactions with their favorite team and where one dude’s silly idea can become adopted by actual professional baseball players.

“A lot of the fans, you can recognize coming to games on a regular basis,” said Indians right-fielder Lonnie Chisenhall. “That’s a neat thing to have, especially when something like ‘Party at Napoli’s’ takes off.”

Fun story: Crowe made a T-shirt aimed at Chisenhall last season. It said “Sweep the Leg, Lonnie” — an allusion to “Karate Kid.” But it never took off like “Party at Napoli’s.”

“That party,” Chisenhall says. “We’re celebrating as a team after we win a game and [Napoli] is our veteran guy and odds are it’s at his place.”

Wait, so are there actual parties at Napoli’s?

“Once or twice,” Chisenhall says.

“There might have been a couple here and there,” Napoli said.

What happens?

“I can’t tell ya,” Chisenhall laughs.

Nate Crowe hasn’t gotten an invite yet. And that’s fine with him. His favorite team winning the World Series after 68 years and knowing he had even a tiny part of it — that would be enough.

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Mike Oz is the editor of Big League Stew on Yahoo Sports. Have a tip? Email him at mikeozstew@yahoo.com or follow him on Twitter! Follow @MikeOz