What you reply to someone who has just said something completely stupid and obvious.
Joe: Wow it sure is hot here in the deserthuh?
Tom: Well thank you captain obvious...
By Delcine
"Thank You Captain Obvious"
A phrase generally used to indicate that someone, i.e. Captain Obvious, has just uttered something that everyone can see. Of course, this statement is usually uttered by someone who is only bright enough to see obvious things.