Eminem is a busy guy — he isn't exactly the most accessible artist to work with, which is part of the reason his guest spots on songs like Lil Wayne's "Drop the World" and Drake's "Forever" are such big deals. He doesn't just do it for anybody, because not just anybody can keep up with him. So when the track list for B.o.B's debut album The Adventures of Bobby Ray was released, it was a surprise to see Em's name included.

B.o.B scored a guest spot from an enthusiastic Eminem on "Airplanes (Part II)," also featuring Hayley Williams of Paramore. Marshall Mathers said manager Paul Rosenberg introduced him to B.o.B's work, starting with his first mixtape Cloud 9, and he liked what he heard.

"Paul Rosenberg played him the Cloud 9 mixtape and it kind of gave him an idea of what my music [sounds like]," B.o.B explained. "Eventually he started playing Em more of my stuff and was keeping him updated on my progress and eventually he wanted to get in the studio with me, so that was a gift."

According to B.o.B, working in the studio with Em was like being in a laboratory with a mad scientist, watching and observing how everything works. But he was happy to find that while each artist has different methods, they're all trying to find that zone.

"It's really reassuring to know that every artist has a way of working but it's all ... the essence of it all is to get in that vibe and to get in that zone, and everybody has a different way to get in that zone," B.o.B offered. "It's good to see a different way, because you know, 'OK, I can do this or I can do that.' It kind of showed me where I was thinking inside of a box and where I can open up even more."

What do you think of the collaboration between Eminem and B.o.B? Let us know in the comments below!