Imagine if Peter Parker had never become Spider-Man. Instead, he kept getting bullied, yet still had the compulsion to dress in spandex. And he started a band.

He would probably sound a lot like Ninja Sex Party.

The comedy songwriting pair of Daniel Avidan and Brian Wecht have created the quintessential Internet Band: Their music, first published on YouTube, is heavily inspired by 1980s pop and hair metal, as if Belinda Carlisle were the lead singer of Van Halen. You’d be correct in guessing the lyrics are raunchy, but they’re also ridiculous and earnest. Their advice for combating bullies? “You put your hands in the air and then stick out your rear end / And then you wiggle it real hard and you hug your closest friend.”

The band has been going for almost a decade, which is a millennium in Internet years. Their YouTube channel has reached 1.2 million subscribers, and millions more have streamed their songs on Spotify. Their album, “Cool Patrol,” reached No. 2 on Billboard’s rock albums this year, beating Imagine Dragons. And they’ve held the top spot for comedy albums for the past seven weeks. Their most-watched music video, the aforementioned anti-bully anthem “Cool Patrol,” has more than 12 million views.

Still, when Conan O’Brien had Ninja Sex Party play on the late-night TV show in September, Wecht couldn’t help but feel nervous.

Wecht, 43, is a retired theoretical physicist who has years of live musical and comedy performances under his belt. Becoming Internet famous means millions of people are familiar with his persona, Ninja Brian. But about 20 seconds into his Conan performance, Wecht’s hands trembled over his keyboard. He can’t remember the last time he visibly quaked from being nervous. “It’s the first thing we’ve ever done that doesn’t feel niche,” he said of the performance.

For the first time in years, Avidan said, they didn’t know who was watching them. At a concert earlier this month at the Fillmore, the sold-out, 2,000-strong crowd knew every word, every inside joke, every character that appeared on stage. When Ninja Brian deliberately messed with the rest of the band’s instruments, the fans knew that the character is meant to be a villainous, yet fun, foil.

Late night TV watchers don’t have that context. The band’s fans, however, know exactly what they’re getting into at a Ninja Sex Party show.

“When the camera’s on, you have no idea who that’s going out to and who might be watching,” said Avidan, 39, whose stage persona is Danny Sexbang and also performs as the other half of the YouTube comedy duo Game Grumps. “That was the biggest reason we were more nervous than we thought we were [on Conan]. When we realized how big the come down was, physically and emotionally, that’s when we realized it was a big deal.”

Avidan has always wanted to be a rock star. His first years out of high school were spent in small bands aping shoegaze Brit rock bands like Radiohead. Wecht was introduced to Avidan over email through mutual friends in the New York improv comedy circuit.

“He came to me and was like, ‘Here’s the idea, it’s called Ninja Sex Party. I think you’d be a ninja, and that’s all I got so far,’" Wecht said. “You didn’t have Danny Sexbang the name originally, right? It was Sweet Nuts, right?”

“No, I did have Sexbang. Danny Sweet Nuts was the name of my ‘Guitar Hero’ character. Before we met, I thought, ‘That needs to be more explosive,’” Avidan said.

Their first video in 2009 was “I Just Want To (Dance),” which was a Queenlike ballad rocker about a ninja-cum-dancer. Their first big “break” came via their friend Donald Glover, whom they met while they all worked and studied at the Upright Citizens Brigade, the famed improv and sketch comedy group. On his blog, Glover featured Ninja Sex Party’s second video, “The Decision,” after Avidan helped Glover’s father get into a UCB show.

“The video got 6,000 YouTube views, and we were like, ‘We did it! That’s it baby!’” Avidan said. “I remember getting teary eyed. Even though you look back at that and go, ‘Come on dude, get it together,’ at the time after years of bands where I couldn’t even get a hundred people to listen, there was this sudden feeling of people liking a thing we did. It’s the same feeling no matter how big the scale around it is."

In 2013, the band had 40,000 YouTube subscribers. Then YouTube gaming personality Arin “Egoraptor” Hanson invited Avidan to be his co-host on Game Grumps, which at the time had 250,000 subscribers.

Avidan’s response? “How could anyone be that famous?”

Game Grumps now boasts 4.8 million subscribers. They upload two to three new videos a day, and their videos collectively have more than 4.3 billion views.

But the changing landscape of YouTube algorithms and different waves of “influencers” coming and going can create enormous pressure. Avidan’s glad this viral fame has come during his 30s, when he feels more in control of his emotions. Age has given him distance from the anxieties of having to produce and perform for people online every day.

“The thing about YouTube is that there’s no one to tell you to stop,” Avidan said. “There’s no one to tell you, ‘All right, your job is done for the day. Go home.' There’s also the constant knowledge that as soon as you stop, there’s someone else still going, which is why so many YouTubers suffer extreme burnout."

Because of the band’s slow burn toward success, Wecht said, it no longer relies on YouTube as its primary source of revenue and attention. Spotify is about to become its most profitable digital partner, giving the band a solid and diverse revenue set that isn’t beholden to algorithms — including album sales, merchandise and touring. (Most of Ninja Sex Party’s audience is 18 to 24 years old, a generation unfamiliar with the concept of buying music.)

The band is independent, and the duo do much of the work themselves. Their tour manager, JP Hasson — who works with several YouTube personalities like Jacksepticeye (20.5 million subscribers), as well as other comedy products like the show “Bob’s Burgers” and comedy duo Tim & Eric — also doubles as a stage hand and even their villainous laser dinosaur character, who appears on stage and is defeated only by the “positive energy” of the crowd.

And the Fillmore crowd had exuberant positive energy. Phones lit up like lighters during a balladic version of one of the band’s biggest hits, “Dinosaur Laser Fight.” Part of the act involves shouting vulgarities at Ninja Brian, but it felt like good-natured ribbing. The crowd chanted the names of Avidan’s parents, who were in attendance. Danny Sexbang ended the show with a message: Everyone, no matter what their background, is welcome to the party.

“They go the extra mile for us,” Avidan said of their fans, who typically line up for shows eight hours in advance. “Who knows how long this lasts? It feels like it’s been trending upward. But if it ever goes sideways, it won’t be because we didn’t care enough.”

“It never ceases to amaze me that we have these crowds,” Wecht said. “How is this even possible?”

After the show, Avidan went to a desk to sign a stack of posters and shirts. The pair later met lingering fans behind the venue. Like superheroes, they understood their power, and the responsibility they hold over their fans.