know beans about

verb2

1. •
   (US) To know something, even if only a little, about.

   • But the great artist doesn't know "beans" about driving oxen. He has put his driver on the "off" side of the yoke. — 1881
2. •
   (US) To know nothing, or almost nothing, about.

   • His primary opponent, Raphael Herman, is a real estate salesman who frankly admits he knows beans about insurance. — 1986