I have worked in my current area of expertise for the last 20 years or so. It's in Aviation, can't say exactly what or for who as it's a relatively small community (for my role) and it would be VERY outing. Before this, my only other "job" that I did for a few years was dancing (yes, that kind 
). So I don't have massive experience of the world of work.
But I was chatting with some people in a bar over the weekend and conversation turned to jobs and then to my role. I was telling them about some stuff which is perfectly normal to me, but was absolutely news to them.
For instance . .
When a plane is "parked" and everything is switched off, the aircraft is referred to as being "Cold and dark".
If a helicopter has engine failure, it won't just fall out of the sky. The pilots are trained in a procedure called "autorotation" and can usually land safely even if the engine isn't running at all.
All British Airways flights use the call sign "Speed Bird". It's unique and no other airline in the world uses it.
Last one . .
Pilots can't wear polarised sunglasses. They make the electronic displays on the flight deck appear black, and you can't read any information from them.
So, what do you know from your jobs that is mundane for you but which most people wouldn't have a clue/be surprised by?