Maura: So if we say that I gave my friend a heads up about the test, it means that I told her about the test, or I warned her about the test, before it happened so that she could prepare and be ready for the test.
Harp: Exactly. And the possible origin for this expression comes from baseball.
Maura: Like so many American expressions.
Harp: Exactly. So at a baseball game, when someone yells heads up, it’s because a ball is coming towards you. So you put your head up to see the ball so you can move out of the way and so it doesn’t hit you.
Maura: Right. So if you think about it, when that person yells, heads up they’re giving you a warning that the ball is coming.
Harp: Exactly.