Indicating that her opponent is masturbating because his partner won’t perform oral sex on him, although she would be willing to perform cunnilingus on AB — which is a reference to the first verse. Alternatively, a suggestion that her male opponent performs oral sex on his girlfriend, without reciprocity. The interjection of ‘the gun, too’ serves as a contextual bridge from the preceding violent imagery to the re-assertion of the sexual-domination theme.
“Poon” of course means “vagina.”
Also, AB exercises a nice little enjambment here: “cock” both finishes the first line and starts the second one.