Wiktionary
vb. 1 (context chiefly US idiomatic English) To know something, even if only a little, about. 2 (context chiefly US idiomatic English) To know nothing, or almost nothing, about.
Usage examples of "know beans about".
We dont know beans about them, and here theyve been staring up our asses.
This guy, I didn't know beans about, but from what I've read since, he's a very solid citizen.
She doesn't know beans about an appraiser being hired, but it all sounds legitimate-like something her husband would have done toward the end-so she hands the letters over to Guy and he takes them away.
Hell, I could do it myself and I don't know beans about that stuff.
He frequently didn't know beans about the information he looked at, but was honest enough to tell his superiors that.
And he did not know beans about Star, although he was very complimentary to May and me.
Ryan still didn't know beans about counter-surveillance techniques.
I don't know beans about field work and tree-chopping but I can already see you'll be better than her.