You’ve got no idea what you’re talking about
This sort of phrases is used by toxic people who want to ruin your self-esteem by telling you how badly you are informed about the stuff you are talking about. These words are used to make you feel intellectually inferior to others. It is embarrassing when this phrase is articulated around other people. However, if you are smart, you will understand that the person who says this phrase wants to humiliate you in front of someone else.