Imagine that you go in to work on Monday, and your boss tells you that you're getting a raise. Your pay will be doubled. Great!
On Tuesday, you get a letter from your landlord. Beginning next month, your rent will be doubled.
On Wednesday, you go shopping and discover that a loaf of bread costs twice what it did last week.
On Thursday, you go to buy gas. Turns out, the price at the Shell station is double what it was before.