A phrase often used towards someone who states the obvious.

meaning 'well of course dumbass!'
other phrases like this include grass is green

duh.

what you say when someone says something very obvious.

Stating something obvious, this is a sarcastic way of saying "It's very obvious, you can shut up now."

The victim can follow up with "Fuck you Watson" or similar to defend themselves.

A very sarcastic way of saying: obviosly.
(Sherlock Holmes was a detective in a classic series of books.)

It's like the person said something that was pointing out the obvious....kinda like "no duhh!"

A full of sarcasm phrase used to state what you're saying is obvious.