Interest-On-Interest

It's kind of a kitschy, pithy maxim that frames just how much debt a given company or person is carrying. "Even the interest on the interest is a big number," meaning that if a company has a billion dollars of debt at 6%, they're paying $60 million a year to rent that bil.

So if you had interest on that $60 million of, say, 6%, then the interest on the interest would be $3.6 million...still a lot of dough in the real world.