She let me cactus the cat backwards
Here Vic is using a pair of euphemisms to say that he fucked a girl from the back. A cactus is sharp and thorny — likely to stab someone (even penetrate). While “the cat” is someone’s pussy. Subtle but very descriptive.
To help improve the meaning of these lyrics, visit "Tweakin" by Vic Mensa (Ft. Chance The Rapper) Lyrics and leave a comment on the lyrics box