Explanation: The Romans were quite fond of omens - augury. Good omens, bad omens, all determining whether to go ahead with a plan or pull back. Even the mythical founding of the city was based on an omen - how many birds were seen by Romulus.
One method of omen-taking was by seeing if sacred chickens would eat at the moment - if they would eat eagerly, it was a good omen; it they would not, it was a bad omen. One irate Roman admiral is said to have tossed the chickens into the ocean after finding they would not eat that day, saying "If they will not eat, let them drink!"
He lost the ensuing battle and was shamed and removed from command by the Senate when he returned.