I'm Raymond Andrew Joubert, faggot, I can pack a bag
With your body after I rape and kill you on tracks-in drag
Space Cowboy, no joker, I crack Steve Miller's skull
If he has the balls to claim that he's iller, y'all

from The Ruler of Men – Roger That Lyrics on Rap Genius

Meaning

These 4 bars all tie in, vaguely, to Stephen King’s 1992 novel Gerald’s Game.

In the book, Raymond Andrew Joubert is revealed to be the name of a murderer, rapist and cannibal the main character initially believes is the personification of death himself. Raymond Joubert, in addition to his many other horrific vices, is apparently a cross-dresser, hence the “in drag” remark (Stephen King loves to make serial killers in his books cross-dressers, for some reason)

The “space cowboy” and the lines that follow refer to the Steve Miller Band’s 1973 song The Joker, which is referenced heavily in Gerald’s Game. The song begins with “some people call me the space cowboy."
It doesn’t explain why a rapper is threatening Steve Miller, though

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