Lyric discussion by slow learner 

I think it's supposed to be "there ain't no cowboy in my hat." He wants to be free of people who know what he "really is" so that he can treat his partner better than he's treated anyone before.

he's, literally or figuratively, killing off anyone who might know or care that he's an impostor or fraud (aren't we all) and using their bodies (or what they know about him) to nourish the set for his relationship with his partner. Anyone that knows that he's not always been a puppy dog or cowboy has to go if he's going to be the man he wants to be.

Or you could say that he's imagining what it would be like to act on that urge to kill embarrassing friends and dudely competition/anyone who stares too long at his partner's ass. I think we've all been there.

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