When Fall Out Boy announced their reunion via their 'My Songs Know What You Did in the Dark (Light Em Up)' video, longtime fans were both excited and confused. What the heck was 2 Chainz doing there?!

The band would like to explain.

"We went out for dinner, talked about the idea, played him the song ... the night I went out with 2 Chainz to talk about this, we took a picture together," bassist Pete Wentz told MTV News. "He posted it on the Internet like, 'Fall Out Boy featuring 2 Chainz.' Kids were like, 'That's not real.' The stuff we were doing was so crazy, it was like disbelief," Wentz said of the fan reactions. "It was like, 'Nah. Definitely they're gonna be playing on a TV show, but not [working with] rappers.'"

As to whether or not Wentz and the rest of FOB, who share a label with 2 Chainz on Island Def Jam, was only slightly cryptic in his response -- there will be more 2 Chainz, but he won't say in what capacity. "There's definitely some further creative collaborations that'll be happening sooner rather than later, some with him."