Quick pitch

From BR Bullpen

A quick pitch is a pitch that is made before the batter has had time to settle down in the batter's box and without the pitcher making an appropriate pause during his delivery. A quick pitch is illegal and potentially dangerous, as the batter is not in a position to react properly and get out of the way if the pitch is too far inside. With men on base, a quick pitch is a balk; it will be called a ball when no one is on base. It is considered a type of illegal pitch.