They ain't in the cypher of some lifers
Lupe stated in the line before that their raps come off flat because they aren’t in his inner circle.
Cyphers take place in circles and groups.
Prisons populations are notorious for dividing into cliques and groups including along ethnic and gang affiliations. Prisoners serving life sentences will typically be housed in different cell blocks than those inside for shorter sentences and less serious crimes.
By lifers in the cypher he means rappers not being good enough to be included in that elite circle of artists who have managed to sustain a long and successful career in the music business. This is made apparent in the following line when he says “them niggas probation/soon to be leaving Rikers.” Rikers Island holds prisoners temporarily so if you violated your probation for a minor offense you would serve your brief stint there then be on your way. So the line simply put is saying rappers careers are short and if you don’t make it past the probation part of your career the fans will let you know and just like that you’re another failed rapper sent into oblivion.
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