what's the meaning of this phrase?
From the situations in which I've heard it being used, I get a meaning like "wake up" or "open your eyes" out of it.
Can somebody support this?
Yes. It's rude.
It can mean "Pay attention!" or specifically "Pay attention to the real-life situation in front of you."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.