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Lupe Fiasco and Kid Cudi were once friends running in the same musical circles, but it became apparent that was no longer the case during a Twitter exchange earlier this month. And now Lupe is explaining why things got so heated.

"He was a good dude; I loved his music and I just got a love for dude," the rapper, whose new album, Tetsuo & Youth, is out this week, told "Sway in the Morning," expanding on his "f--k him" comment from earlier in the interview (the entire 37-minute sit-down is worth a watch, as he discusses his relationship with Atlantic Records, the new album, Azealia Banks and more).

"And I know that certain people, when they get fame really quick, it'll tear you apart, it'll f--k you up. And it's good to kind of have people -- even if we not, we not gonna eat dinner together every night or do no sh-t like that, but I genuinely f--k with you, I'm a real n---a and when I f--k with you, I f--k with you. So we cool."

But things apparently got tense last year, after the Chicago rapper was offering on Twitter to do guest verses for his fans, and Cudder didn't exactly approve.

"I told my fans, 'Yo, if you want a Lupe verse, I'll write it for you for $500. It'll be yours; you can't put it on Twitter -- it's yours. Don't leak the sh-t or do whatever; it's yours.' And Cudi went on Twitter and was like, 'Yo, Lupe, what you gonna do with that money?'...I'm thinking he joking."

Lu says Cudi then stopped directly addressing him in tweets, but he caught wind of the Cleveland native's fans saying stuff like "f--k Lupe."

"I said, 'Yo, gimme this bitch ass n---a Cudi's number, if I see him, I'm knockin' him the f--k out," Lupe continued. "'Cause I wanna get to the bottom of what the f--k you talkin' about. Because it's me. The same n---a you went in Complex and was like, one of the only n---as who reached out to me genuinely and had love for me was Lupe. But now I'm some f--kin' thief? Now I can't find you? Nobody knows where you are?"

He says he has been trying to get in touch with him for six months, to no avail.

"Cudi, let's settle this," he said. "Talk to me, before I f--k you up."