My dad used to ask me that. Mainly I think because he couldn't quite get his head around the fact that I would come home two or three times a year and get several weeks off. Not really realising that I was a company man (With BP) and leave was part of my pay & conditions. He of course only got two weeks holiday a year. It seemed to puzzle him that they would fly me home from anywhere in the world for a few weeks, then fly me out somewhere else at a later date.
Dad was in the RAF, went out to Habbaniyah? Iraq in 1937, and never got home until 1943! No 6 month trips for him!