Being of bare sustenance/degraded status.
Minimal comfort level.
Having little to no swag.
Being that dough = money, grain therefore is less than money, as it is less than dough. Taking this concept, grain thus becomes a term describing all that is lame and uncool.
Also derived from low quality cinema showing a picture quality described as "grainy"
"You a grainy looking fool"
"You failed the test? Damn boy you bout grainy as hell."
2. That grain had me out of my mind.