Marvelously thinking out of the box EllieGato. Did you check with Turkish native speaking friends? I could if you didn't. Do you consider the possibility or suggest he could be Turkish?
The person who told me that speaks only English but had an older brother who spent time in the middle east while in the military. She can't ask him as he is no longer living. But she remembers him saying that phrase when people asked him what he was going to do next, and at some point he explained the meaning in an email to her.
I dont mean to imply that I believe he is Middle Eastern. But maybe his job or station included working with people who spoke Turkish... military or private contractor. Maybe it's a phrase he had heard many times, or had to say many times.
When will you be finished with...?
I dunno
Where will you go next?
I dunno
Who is your leader?
I dunno
What is the plan?
I dunno