Bread & Butter

So I'm having a conversation with a friend, via texting.
I say, "...You can do that, if that's your bread and butter."
A phrase I don't use very often, but a good one none the less. Underrated even. Maybe. Kinda.
No more than 5 minutes later, while watching, "Return to Paradise" on Netflix, Joaquin Phoenix is
wheeling a janky bicycle up a hill.
His friends tell him to ditch the bike, in which Joaquin responds with,
"This is his last bike, that's his bread and butter."

-Dom