The Dr. Fox effect is when people think a speaker or teacher is very smart and knows a lot about a topic just because they talk in a confident and charismatic way, even if what they are saying doesn't make any sense or isn't true.
Let's say a teacher comes to class and starts talking about a subject like math, but they really don't know anything about it. However, they talk fluently, use big words, and have a confident manner, so the students think this teacher is very knowledgeable and they start to believe everything the teacher says.
Even if the teacher presents bad, false or completely fabricated information, the students don't realize it since they are too busy focusing on the teacher's confidence and charisma, rather than the substance of what they're teaching.
This phenomenon can be dangerous because it can lead to misinformation or wrong solutions to problems. That's why it's important to always double-check the information we receive, even if it comes from someone who speaks with great confidence and authority.