You could holler "bowling balls" and it wouldn't matter. What does matter is consistency. I started training my girls when they were a day old by feeding fresh cut grass while saying "Here, chickie, chickie" to them. When they went out in the coop I used an empty cool whip container with the kitchen trimmings to carry their treats out to them. I rattled the container and said "Here, chickie, chickie" the whole time. Now that they free range, all I have to do is carry the cool whip container out and call them the same way and they come running no matter where they are. I also feed their treats around the same time each day, after supper. They're creatures of habit, so consistency on your part will pay off. It does take time though, so be patient.