It’s when you shine four lights into Captain Picard’s eyes, ask him how many there are, and torture him for not saying five.

(It’s a psychological abuse tactic where you try to make the victim doubt their own sanity by questioning obvious facts. It’s completely meaningless in public discourse since facts are political, nobody understands power dynamics, and anything that can be a stand-in for “thing I don’t like” can be applied to anything else.)