Currently I am learning English language. I found something that I don't know what it means.
Some people on the internet put their disclaimer using one sentence
I have no idea what I'm talking about
or something with
I have no idea bla bla bla...
When somebody says "you're smart," make sure they don't mean "I have no idea what you're talking about" - Ariana Lenarsky tweet.
I found the meaning of that sentence on random forum that "I have no idea" means "I don't know at all". There is no clear explanation, though.
What exactly does it mean?