1. When I saw that Persephone had colored on the walls, I read her the riot act. (Oh, and I did - I'm a mean mommy like that).
Meaning: To severely scold or warn someone.
Origin: In 1714 the British Parliament passed the Riot Act. It said if twelve or more people gathered "illegally, riotously, and tumultuously," a magistrate could command them to break up and leave just by reading the opening words of the Riot Act. If they didn't leave within the hour, they were guilty of breaking the law and were given a severe punishment. As the years went by, "reading someone the riot act" came to mean warning a person of severe punishment in the strongest possible terms if he or she did not stop a certain activity.
2. That antique is a fake. This is the real McCoy.
Meaning: the genuine article; not fake or a copy.
Origin: There was a boxer in the late 1800s who called himself Kid McCoy. His real name was Norman Selby. He was a great fighter and so popular that other boxers started calling themselves Kid McCoy. So Mr. Selby had to bill himself as "the real McCoy."
3. "What can you see in the tall, old tree" was a false clue in the scavenger hunt; a red herring to lead us off the trail.
Meaning: Something deliberately misleading to divert your attention from the main subject; something irrelevant that confuses an issue.
Origin: A red herring is a fish that has been pickled in such a way that it turns reddish (due to vinegar and spices). It has a very strong odor. Centuries ago, red herring was used to teach hunting dogs to follow a trail. It was dragged on the ground and the dogs followed its scent. Later, people who hated hunting dragged a red herring across the path of the fox the dogs were chasing, confusing the dogs. They would stop following the fox, and follow the smell of the herring. Sometimes escaping crooks also used red herrings to coverup their own scents so the blood hounds couldn't find them. "Red Herring" has been a popular term since the 19th century.