“Devil’s advocate” is a person who advocates an opposing view, often for the sake of argument. Example: I agree with your plan. I’m just playing the devil’s advocate so you’ll know what the opposition.
Idiom of the day: Jump the gun. Example: He shouted at me before I had time to explain, but later he apologised for jumping the gun. Origin: This phrase originates from races, such as horse races or track and field.