Last week he was nothin', boxers stain
Last week he was nothing. Nothing sounds like nutting (ejaculation) so he made a word-play with boxer’s stains. None of us likes wearing boxer’s with white stains (I hope) so he is basically saying that he wasn’t on demand like now.
To help improve the meaning of these lyrics, visit "America" by Mac Miller (Ft. Casey Veggies & Joey BADA$$) Lyrics 12 and leave a comment on the lyrics box