Jigga What? Fall Out Boy Get A Hand From Jay-Z On Infinity

Island Def Jam president makes an unexpected cameo on band's upcoming LP.

The most head-scratchingly excellent moment on Fall Out Boy's Infinity on High isn't the electronic punch of first single "This Ain't a Scene, It's an Arms Race," the trilling pseudo strings of the Babyface-produced ballad or the jarring R&B/hardcore mix of "Carpal Tunnel of Love."

It's actually the collision of worlds that occurs in the record's opening moments, during the intro to the song "Car Crash Hearts," when Island Def Jam president/ hip-hop legend Jay-Z shows up to kick off the festivities.

In fact, Hov's voice is the first you hear on Infinity, booming over a bed of crunchy guitars, putting the critics "that said it would never happen" on blast and dedicating the album "to the fans that supported us/ the fans who held us down."

To say that it's a rather eye-opening cameo is an understatement. Which is pretty much how the guys in Fall Out Boy wanted it.

"It's so important to begin strong, and I don't think you can start much stronger than this," bassist Pete Wentz told MTV News. "This is a message recorded directly to our fans — it's one of the few times on the record where we speak directly to them, and I think it's amazing that Jay is having a conversation with our fans. Also, it's a snapshot of where we are right now. And years from now, when I'm laying in some gutter somewhere, Jay-Z will still be on this record."

Hey, sorta like Oscar Wilde! Needless to say, details on Infinity are coming at a fast and furious clip these days, what with last week's leaking of "Carpal Tunnel" (see "Fall Out Boy Leak New Track") and the big revelation of the album's title (see "Fall Out Boy Exclusive: Pete Wentz Reveals LP Title, Details On Single"). And according to Wentz, that's the same way the Jay collaboration came to be: on the fly and almost completely without rhyme or reason.

"I think he recorded some of it in Australia while we were sleeping. It was insane," he laughed. "We called him up and thought we were gonna talk to his assistant. Then he answers the phone, like, 'Yo, this is Hov,' and we were like, 'Um ...' It just happened like that. And it was pretty crazy."

But with Jay already shouting out both My Chemical Romance and MySpace on his new album Kingdom Come, does his appearance on Fall Out Boy's new LP mean that the rap kingpin is looking to expand his empire into — gasp — the "scene"?

"Don't hold your breath waiting for him to break out the eyeliner and scene hair. I think he's just a smart dude," Wentz said. "He appreciates the energy some of the bands in our scene bring. I think he also likes the viral marketing that goes on here. But that doesn't mean we wouldn't love to do something more with him. Let's be honest, his new record just dropped, so I'm gonna guess he's a pretty busy guy. Never say never, though. You can always hope."