Split it then I roll it then light it up like it's Independence Day I got a bottle rocket put it in the air
Spit it means his rap/freestyle flow like when someone spits saliva
After saying hard verses, they write them on paper. MGK is saying he roll his rap sheet up and smoke it (light it) means that he’s dope (cool,nice,awesome, etc).When he light it, he compares himself to 4th of July (mainly towards fireworks and the smoke that surrounds the area).
Bottle rocket in the air could mean he’s fly or simply he has a bottle rocket in the air (which could be champagne,beverage, etc.)
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