I raised my kids with a "1, 2, 3" system. Stems from an old story.
In the old west, a guy got married. He and his bride came out of the church, he lifted her into the buggy seat, and was walking around to get in. Someone shot off a shotgun, and his horse reared. He grabbed the halter, pulled the horse's head down, and looked in his eye. "That's one."
On the way to the ranch, a rattler was across the trail, and the horse reared. Guy got down, shot the snake, and again looked the horse in the eye. "That's two."
At the ranch, some friends had taken a short cut and beat the honeymooners to the house; they were having a shivarie. Shot guns, dynamite, bugles, etc. The horse read up again. Guy didn't say a word. Got off the buggy seat,drew his gun, and shot the horse dead in the traces. His new wife started right up on him. "You shouldn't have done that. It's your friends making all that foolish noise. You should not have shot the horse!" He looked at her and said, "That's one."
My kids were pretty good at not letting it get past two.