In the Land Cruiser Jeep with the Mac-10 by the seats
For the jackers, the jealous-ass crackers in the *blue suits*
I'll make you prove that it's bulletproof!
Despite leaving the crime game for the rap game, Biggie still needs to keep a machine gun with him at all times, lest people try to rob him
The siren sound effect was inserted to censor the words “blue suits”, a reference to envious white cops who hope to rob Biggie under color of law (it also rhymes with bulletproof). You can hear him say “blue suits” in the acapella.
I took “Jackers” to be a pun referring to car-jackers, but primarily a word short for “jealous-ass crackers”. He was calling white cops, Jackers aka Jealous-ass crackers. However, also using to word itself to show they were trying to rob him (because they were white cops with average pay and he was a rich black man and convict thus making them jealous of him) and by doing so they would have to prove their vests were bullet proof.
To help improve the meaning of these lyrics, visit "Machine Gun Funk" by The Notorious B.I.G. Lyrics and leave a comment on the lyrics box