When someone says, "I'm going to take you down a few notches," it means they are planning to humble or criticize you, often with the intention of bringing you down a peg or two. The phrase "take you down a few notches" comes from the concept of a notched scale or ladder, where each notch represents a level of superiority or arrogance.
So, if someone says this to you, they are suggesting that you have been acting too confident, boastful, or arrogant, and they intend to challenge or diminish your ego by pointing out your flaws, mistakes, or weaknesses. It's a way of telling you to be more modest or less self-assured, typically in response to behavior that the person finds objectionable or overbearing.
It's essential to consider the context and tone when someone says this phrase, as it can be meant humorously between friends or seriously as a form of confrontation or criticism. It's generally not a positive remark and might be intended to make you reflect on your behavior or attitude.