Seeing as the Rockstar Energy Drink Mayhem Festival kicks off at San Manuel Amphitheater this weekend, we thought it high time to catch up with Robb Flynn, lead singer and guitarist of veteran Oakland metal band Machine Head. Besides touring in support of band's seventh album (Unto the Locust), he's recently coped with hernias, surgery, and getting hit by a taxi.

Undeterred by 2012's series of unfortunate events, Machine Head are back in the studio working on an album scheduled for release next year. Earlier this week, they announced a new bass player (Jared MacEachern), selected via an open audition process online. We asked Flynn about the auditions, his biological parents (he's adopted), and, you know, his balls.

When you held bass player auditions by email, how many video submissions did you get?

We got well over 500.

Did you watch all of them?

I did. I watched all of them. I'm a masochist like that.

Was this like American Idol, where some people grossly overestimate their abilities, and other people just blow you away?

(Laughs.) I tell you what, the one thing that was really cool — we actually put it up on our Facebook –was this guy [Frank Memolo] with one hand auditioned. And it fuckin' — I swear to God — it made me cry. It was fuckin' so awesome…to see this dude with one hand playing “This Is the End,” which is the hardest song of all. I mean, it's a million miles an hour, just super fast, a million notes. This dude was just putting every ounce of his heart out there, and it was so cool. I'd like to put him up onstage. I don't know if he's coming to the show, but I'd love to get him up onstage and have him jam with us. That would be rad.

I was going to ask you where you think your musical talent comes from, but then I read that you're adopted. Do you know whether your biological parents were musicians?

I don't know my birth parents. No one in my adoptive family was musical. We would listen to music. It's kind of funny because I wasn't raised with metal. All of my early musical experience was the Beatles.

Have you ever tried to seek out your biological parents? You never know — they might be Machine Head fans.

I've really struggled with it, honestly. I've really struggled with it. For the longest time I just fuckin' hated them. Just never wanted anything to do with them. I wrote a song on our record Through the Ashes with Empires, and the song was called “Left Unfinished.” And it was just basically a “fuck you” to them. In recent times, I've thought about [trying to find my biological parents]. I don't know. I don't know if they're going to care.

They'd certainly have something to be proud of, based on the career you've made for yourself.

I definitely consider myself lucky. I've met thousands of people who didn't get adopted and went through foster care systems for years and years and years, and they were just fuckin' brutal and harrowing. I'm not gonna sit here and fuckin' cry in my beer about it. I definitely was one of the fortunate ones, adopted around six months old. I had three foster parents. My [adoptive] parents told me that much — there were three sets of foster parents by the time I was six months old, and then they adopted me. I definitely was able to get into a good family, so I consider myself fortunate in that sense, for sure.

I saw you open for Dethklok in New York last year, and shortly before, you had surgery. Then the day of the show, you got hit by a taxi, right where the surgery had been. You've been rather open about what kind of surgery this was, so I feel like I can ask: how are your balls doing?

Thank you for asking about my balls. I appreciate that. My balls are doing great. I had my guts in my nuts. The surgery was for a double hernia. One of the hernias was above my waistline. The other one, actually, my intestines were dropping down into my nut sack.

I had that one for three months. It wasn't actually that bad, it just looked really gross. It looked basically like I had a third nut. But, you know, you just push it back in, and it just goes back in and stays in.

But somewhere along the Dethklok tour, it just started getting kind of bad. I'd get offstage after shows, and I'd try to push it back in, and it wouldn't go in. I was like, “Uh, I don't know if this is good. I don't know how much longer I can last.” I forget what show it was, but one of the shows, I got offstage, and I laid down in the dressing room for about an hour, and I was just trying to push this gigantic third nut back into my guts, and it just wouldn't go in, and at that point I couldn't walk…I was like, this is it. I can't even fuckin' stand here. I gotta get this surgery. We jumped off the tour for ten days, and then we resumed the tour.

The first three shows back were rough. I kept telling myself, “Go up there and take it easy. No headbanging. You just had surgery.” I got up there, and I had my brown eye [a.k.a. vodka and Coke], and I was just like, “Fuck it! I don't care how much it hurts! I'll take painkillers later!”

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