It's a dialect thingie.
"Man, you're talking such a humbug!"
"The kids are doin' such a humbug here!"
"Everything else is humbug!"
To happen upon-
To accomplish or benefit from a situation with little or no effort -
To have something of good or bad fortune happen out of the blue- or without expectation-
Void of expectation
On the humbug, I got a raise at work today!
My girl gave me some good loving today on the humbug.
My friend stopped by my house today on the humbug.
2) Derived fortune initiated with no conscience effort or conspiracy
3) Small endeavor that yields significantly greater than expect benefits.
(Applies to previous example context, though definition is incorrect in its specificity)