And the crackers' ass

from Dr. Dre (Ft. Eminem & Skylar Grey) – I Need a Doctor Lyrics on Rap Genius

Meaning

Obviously, that would be Eminem.

“Cracker” comes from “cracking” a whip at black people during slavery.
It is now used in a derogatory manner to offend white people, but can sometimes be embraced like in this case as “nigga” would be.

In addition, “crackers' ass” plays off of “ass crack” in the previous line, a cute reversal.

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