Lil Wayne

3 Peat Tha Carter III
Actually this line is more likely to be in reference of the fact that Adam Sandler is known for putting his closest friends in his movies. So Wayne's saying he's always looking out for his clique like Adam Sandler does.
Hustler Musik Tha Carter II
He means get in the car, kill if you have to, and leave as fast as you can (swerve off)
Go DJ Tha Carter
this lyric from Lil Wayne has a girl wondering how the gun will fire if it is made out of plastic in the following lyric of the song says "you see when ya boy run off" so Lil Wayne has told her the gun is made from plastic as to not worry her
Go DJ Tha Carter
She doesn't understand how his pistol (probably a Glock GmbH) can be so effective, given it's mostly plastic frame.
Go DJ Tha Carter
several pistols, including glocks, are polymer-framed. polymer meaning high strength plastic. however only the outter frame of the gun is plastic.
Fly In Tha Carter II
I don't have anything chrome plated on my Lincoln Continental because I stick to the basics.
Wasted No Ceilings
"dome" is a slang term for "blowjob" and lil wayne(being from louisiana) used this pun referencing the new orleans saints stadium
Mr. Carter Tha Carter III
"I got the floor" is a way of saying he has everyone's attention (the way a public speaker has "the floor" when addressing an audience). But he wants to do better than that; Lil' Wayne wants to be on top (on the "roof") of everything.
Fly In Tha Carter II
This could also be a reference to the fact that Lil' Wayne represents the Bloods gang, which are affiliated with the color red; their rival gang, the Crips, are affiliated with the color blue. Hence, the "blue" rivals he/his gang kills would be "ghosts."
A Milli Tha Carter III
venereal disease refers to the fact that his lyrics are "sick". See my other explanation for the second half.