History of English - illustrated PowerPoint explaining "retro talk." See examples below.
The Whole Nine Yards
Meaning: To try one’s best
History: World War II Fighter pilots received a 9-yard chain of ammunition. Therefore, when a pilot used all of his ammunition on one target, he gave it “the whole 9 yards.”
Let Your Hair Down
Meaning: To relax or be at ease
History: Parisian nobles risked condemnation from their peers if they appeared in public without an elaborate hairdo. Some of the more intricate styles required hours of work, so of course it was a relaxing ritual for these aristocrats to come home at the end of a long day and let their hair down.
More Than You Can Shake a Stick at
Meaning: Having more of something than you need
History: Farmers controlled their sheep by shaking their staffs to indicate where the animals should go. When farmers had more sheep than they could control, it was said they had “more than you can shake a stick at.”
Also of interest:
Understanding Retro Talk the History of English
History of the English Language for Kids