Crumb bum American informal
Someone who is regarded as not good enough to deserve respect or attention, such as a hobo, bum or tramp.
How did he manage to rise to fame from a crumb bum?
I've given that crumb bum 100 dollars to let him go.
Be poor in quality
The food here is crumb bum! I will never come back to this restaurant once again.
I think it's time to remove this crumb bum sofa.
To have no money
Be broke
No food in the house or no money.
A "bum" has long been an Americanism for a tramp. The "crumb" may come from the irritating or useless character of bread crumbs or toaster crumbs, but it is possible (despite the spelling) that the first syllable derives from "crummy" as in worthless, detestable. The internal rhyme solidifies the expression.
To indulge unlikely or fantastical possibilities
He tends to cast beyond the moon, so his moniker is "dreamer".