Ask him about the company's situation and he doesn't know a thing.
Tips
history
From 左传·哀公二十七年: 君子之谋也，始、衷、终皆举之 - a noble's planning considers beginning, middle, and end. The 三 ('three') refers to these three stages: not knowing any of the three means total ignorance.
usage
Often used as polite self-deprecation ('I really don't know anything about this') or to criticize someone uninformed but in a position to know. Frequently follows 问 + 他/她.
