on the grind
Definition: (adjective phrase) working hard
Example: Arnie’s ex-girlfriend tried to frame him for the murder, but he had an alibi: he was on the grind at McDonalds at the time.
“Man, I keep my fitted [hat] cocked, just to show my head line,
But keep it down low when I’m out on the grind.
It’s gotta be New Era man, no matter what they charge,
But its all good ‘cuz I got my Lids* card.”
Grind is a word with a lot of slang meanings. For example, a grindhouse is a movie theater that shows low-budget, often shocking and violent movies. People who are grinding on the dance floor are doing an X-rated move, also called wining, which involves grinding your backside into your partner’s front side. In the US, a grinder--also known as a hoagie, sub, hero, spuckie and many other regional names--is a big sandwich on an Italian bread roll.
Grind was already being used as a synonym for working in the mid-nineteenth century, and it can have a negative connotation. In Mark Twain’s short story The Man Who Corrupted Hadleyburg, Mr. Richards complains that he is “always at the grind, grind, grind, on a salary--another man's slave, and he sitting at home in his slippers, rich and comfortable.” Twenty years before Twain’s tale of small-town humiliation, college students were using it to grumble about their study workload.
In rap music, it is frequently associated with selling drugs on the street corner, and that could be the reason that Lil Flip says he keeps his New Era baseball cap “down low when I’m out on the grind.” That connection is made more explicit in songs like “On the Grind” by Lil Wayne. After a long catalog of the various illegal substances he can provide to customers, he explains, “I'ma be right on the corner, wodie [friend] -- I'm gonna grind.”
* Lids is a US chain store that sells hats, particularly baseball caps.