pig in a python n. especially in demographics, a spike or surge in a statistic measured over time. (source: Double-Tongued Dictionary)
Further reading
What’s the origin of the phrase a country mile? Vida from Rochester, New York, says her husband often uses it, as in “go about a country mile and then make a left.” The expression goes back at least 300 years in the United Kingdom and has long meant...
You know the expression fly in the ointment: It’s that glaring typo on an impressive resume or that first scratch on a brand-new car—the one little flaw that spoils it all. This phrase goes all the way back to the biblical Book of Ecclesiastes! And...