In case anyone is wondering..."Highball?"
Having spent a bit of time as a railway conductor, I've used the term thousands of times. When the dispatch has approved the train to depart the station, it is called being given the highball, and that is the code given on the radio. It originated in the pre-radio days, when a large red ball would be hoisted up a pole signaling the engineer that the track was clear, switches were set, and he was good to go.