NavList:

The recent thread entitled "Is Sextant a generic word?" showes that most of us have been in social situations where we had to explain what we were doing (sextant in hand) to a total stranger with presumably no knowledge of celestial navigation, position finding or even that the sky could tell us something about where we are. This is particularly a problem with the younger generation because they no longer look up but spend most of their time looking down towards their smartphones.

So the "Twitter Cel Nav Challenge" is this -- what would you say in 140 words or less to explain what you are doing?  Assume that if you fail to convince the person, the police will arrive shortly.