I’ve always shied away from posting this expression, believing it the origin was probably too obvious. It must, I thought, refer to the cock strutting around the barnyard and feeling important. That would translate to a person in charge of a situation behaving in the same manner. Turns out the expression began as “rule the roast.” It indeed refers to someone in charge, but the origin was the description of the person in charge of the important task of cutting the roast. The internet has all manner of explanations about the expression that I had always deemed to be to uninteresting to use as a post!