Calling on a read alone, or folding a strong hand.
A hero call is calling with a weak hand on a read alone; a hero fold is folding a strong hand on a read. Example. On a river board of K♠ 8♦ 3♣ 5♥ 2♠, a passive player bets 40 into 40, and folding AA is a hero fold. Live, this is often the right play.