There are folks who pretend to know and have everything.
We know em. A neighbor,friend,church member or someone you see once a week on the way to school or work.
" Say,do you know there is a sale on socks this week at...(interrupted reply) I know.Don't need any,I have plenty."
Here's another...
" You can save money by opening your curtains and let the sun in for li...(another interrupted reply) I already know or I know how to save money. "

Is it a defense mechanism ? You don't want folks to know not having any idea what's going on .

I know the type too -_-.

Usually though the ones who act like they know everything there is to know about something, are the ones who no nothing about the things that really mater.

(sounds corny I know, but still true ^_^)

Good point.