facebook know it all - The kind of people who think they're the only ones who know

The kind of people who think they're the only ones who know anything, and they'll tell you about it every single day on Facebook.

I post about the weather every day. I think I'm a meteorologist now.

I told my brother he didn't know anything. I said, 'I read it on Facebook.'

They asked me if I knew what a constitution was. I said, 'I think it's the same thing as a contract. I’ll check it later.'