e.g. I was already angry with you, and when you forgot to pick me up, that really added fuel to the fire.

Meaning: to make a bad situation worse; to do or say something that causes more trouble, makes someone angrier

Origin: Thousands of years ago the famous Roman historian Livy used this expression. If you pour water on a fire, it goes out. But if you put fuel( like coal or wood) on a fire, you make it burn hotter and brighter. If "fire" represents any kind of trouble, then anything you do to make that trouble worse is "fuel." A similar expression is " fan the flames."

指火上澆油，讓情況更糟糕或讓某人更生氣。源于古羅馬歷史學(xué)家李維。