In Starcraft Broodwar there is the concept of "Ehon Timing". Where does this term come from? What does the term mean exactly?
The term is actually "Ee Han Timing". It is Korean in origin. From liquipedia:
Ee han timing stands for a timing in the game where you have to do damage. For example 2 hatch mutalisks. By doing this build you are (usually) behind economic wise. Therefore you have to do damage or else you will be significantly behind. It is an ee han timing moment. Ee han timing can be translated roughly into 'This one timing'
Additional reference from teamliquid Korean Terminology thread.
Ee-han-timing - 이 한 타이밍
Literally 'this one timing', used to state that if the player misses this timing window, he will have almost no chance of winning.
According to a reddit thread, it was first seen in competitive in Jaedong vs. Stork Game 2 @ Katrina (2007-12-22). This is the same match linked in the teamliquid forum.
The full match appears in this video. If you only want the relevant portion see shorter version, where one of the commentators says it at approximately one second in. (Video links found at the previously mentioned reddit and teamliquid forum threads respectively)