An observer

Hi!
My question is about the word "observer".

The dialaog was:
-"Sir, the taxi has already arrived"
-"You are observing, john" (sarcastic tone)

What does it mean?

Thanks.

I might have expected "You are observant" said in a sarcastic tone, something like: "Wow, you're really observant... nothing gets past you... you saw the big car show up!" Here, "observant" functions as an adjective. "Observing" is a verb and, without further context, I couldn't guess as to the meaning in this very short dialog, assuming that the writer purposefully used "observing" rather than "observant."

I think you meant to write:

"You are observant John..."

This keeps with the sarcastic tone and means that John has merely stated the obvious, i.e. the taxi has arrived which everyone else can see.

In that context (sarcasm) the reply must be "You are observant". To say you are observing, just means you are watching, but to be observant means that you are particularly good at noting what you have seen. This is where the sarcasm comes in; it's hardly being observant to notice that a taxi has arrived, it would be hard to miss, as presumably in this scene the taxi is in full view of the speakers.

Where did you get this dialogue from? It seems to have been incorrectly copied at some point.