See I had to lay the smack down
Act like a X addict
Act now gateway off to the next habitat (habitat)

from Lupe Fiasco – What It Do Lyrics on Rap Genius

Meaning

Wonderful word play here using drug references.

He begins saying he laid the smack down on his homeboys, but can be seen as ending a relationship with smack (dope).

Ecstasy addicts are known to utilize other drugs with the pill (it being a gateway) and so he is off to another habit(at).

With his homeboys in the background he is also saying that he is relocating.

To help improve the meaning of these lyrics, visit “What It Do” by Lupe Fiasco Lyrics and leave a comment on the lyrics box