In the punk-rock world, you’ve got post-hardcore, post-punk, metalcore, melodic hardcore,… In the punk-rock world, you’ve got post-hardcore, post-punk, metalcore, melodic hardcore, grindcore and even a friendly little genre called dudecore. That said, Seattle quintet The Blood Brothers could only be classified as post-everything-core. The band mixes so many punk-influenced styles, their crazed, spastic brand of music will make your head spin like nothing you’ve ever heard.

And tonight at Mr. Small’s Theatre in Millvale, the Blood Brothers will take the stage at 8 p.m. along with Celebration and Chinese Stars.

The Blood Brothers, along with bands like Thursday, Cursive and Saves the Day, came up in an era of underground punk that was never embraced by MTV, but rather gained its reputation through tireless self-booked tours, playing in basements, fire halls and tiny hole-in-the-wall clubs.

Coming together in 1997, while the members were still in high school, the Blood Brothers first played live at a youth center in suburban Seattle – pretty far from the punk rock ideal. Once they’d graduated, though, all confines of the west coast were off, and it was time to tour the country.

“I remember being on the phone or the Internet a lot. But with one of those dial-up connections I’d have to disconnect my phone to contact someone online, then reconnect it to call someone,” co-vocalist Jordan Blilie said during a recent telephone interview. “Back then, putting a tour together on our own was as easy as solving a Rubik’s cube.”

By 2000, the year of the band’s debut album, This Adultery Is Ripe, the Blood Brothers had pieced together a network of friends and bands all over the country. Needless to say, booking a tour became a little easier.

“After a tour or two, we had enough friends to book a tour with. If they’d feed us, give us a place to stay and let us play, that was great. That was the trifecta,” Blilie said.

The band finally broke into the relative punk mainstream with its bombastic and chaotic Burn, Piano Island, Burn in 2003, followed by 2004’s more accessible Crimes and 2006’s back-to-basics Young Machetes. In the seven years since the band’s debut album, the Blood Brothers have put out more albums (five) than most punk bands release in an entire career. Not bad for a band straight out of high school.

So what exactly does post-everything-core sound like? The Blood Brothers tie in features of hardcore punk, indie rock, heavy metal and even jazz to create music beyond any real classification.

The most jarring musical aspect of the Blood Brothers is the dual vocalists. Unlike many punk-esque bands nowadays that employ two voices – usually a singer and a screamer (Taking Back Sunday, Atreyu) – Blilie and his counterpart Johnny Whitney spew their unique vocals like two trains headed off the tracks. Blilie handles the lower register with a singing/screaming voice that resembles Modest Mouse’s Isaac Brock at his creepiest, while Whitney’s voice is wildly high pitched and cutting.

Listening to any song in the band’s five-album catalog, with its pounding guitars played to the point where it sounds like the strings are going to break, as well as drums that are a veritable atomic-bomb explosion, you’ll feel a musical punch in the gut. But when Whitney and Blilie turn up the intensity to a blood-curdling scream level, the Blood Brothers establish their place as one of the most extreme bands around today. No, scratch that. One of the most extreme bands ever.

“I try not to describe what we play, so I use a blanket term like ‘rock band,'” Blilie said. “But the press doesn’t always get us. I mean, when Burn, Piano Island, Burn came out, the UK press was speculating what kind of drugs we were on while writing. They needed something spectacular to describe us I guess, so they were grasping at straws.”

While the UK press was certainly off-base with that supposition, you can’t blame them for trying to figure these guys out – not only is the Blood Brothers’ music a complete whirlwind, their lyrics are also jaw-droppingly odd. Take the title track from Piano Island: “Bulimic rainbows vomit what? Burn, Piano Island, burn! Coconut pupils never shut? Burn, Piano Island, burn!”

Not exactly your average you-broke-my-heart rock-‘n’-roll lyrics.

“We wanted to write about generations of empty youths, disconnected to any sort of feeling or emotion or sympathy, and some of our songs speak to that,” Blilie said, citing his favorite line from “We Ride Skeletal Lighting.”

“The line is ‘The kingdom of heaven reeks of burning witches and dust.’ It speaks to that blankness.”

While it may seem like the Blood Brothers are about as easy to enjoy as a tooth canal, the truth is that under the explosive musical chaos, there are hooks galore, catchy in every song. You might not know what you’re singing about, but you will be definitely be singing along.

For a show that Blilie describes as “Crazy