Show me your work?
How did you get to the answer?
How did you figure it out?
What did you to to get here?
That’s one way to look at it when someone says “Prove it”, the other way is as a dare when you say you can do something and someone says “Prove it” – “Show Me”.
The problem with “Proving it” is that everyone expects the proof to be done now, immediately, this instant, when in many cases it doesn’t go that fast or that quickly.
Our response to “Prove it” should always be the same – “Gimme a few months or a year and I will.”