A Milli Tha Carter III Lil Wayne
in the pen sharing showers means in jail because prison is often referred to as a pen and they have communal showers.
Run This Town The Blueprint 3 Jay Z
blackbirds are crows, which are a symbol of death. their female friends are killers carrying Dillingers (small concealable weapons, after the famous bank robber who concealed guns to rob banks)
Fly In Tha Carter II Lil Wayne
Lil Wayne is saying he's a rap God, so if you don't agree with him it's like you're an athiest (someone who doesn't believe God exists)
Sweetest Girl (Dollar Bill) Carnival Vol II: Memoirs of an Immigrant Wyclef Jean
to add to another explanation for this term, the track most likely refers to a street or part of town near train tracks
Cold Blooded The Coolest Mixtape Lupe Fiasco
to "shed some light" is to help people realize something. ghetto birds (helicopters looking for criminals) literally shine light on criminals to help police find them. Lupe is saying that similarly, his lyrics will help people see/understand street life.
Touch The Sky Late Registration Kanye West
He could not afford the new loafers he purchased. Now, he doesn't have enough money to pay for other things.