A statement thrown into casual conversation that is stressed by the speaker as true, yet unbeknownst to them, has no actual basis in fact. This encourages further hopkisms when the listeners repeat the statement to others.
First person: "Hey did you know that Cameron Diaz was that little girl in E.T.?"
Second person: "Really?"
First person: "Yep, definitely."
Second person: "Are you sure that's not a hopkism?"