One of the most juvenile and fun things to do was to call out “UNCLEARED ONBOARD!” and cover up any screen and paper to prevent the viewing of said info by the uninitiated (aka uncleared.)
Who remembers?
In the mid 1970s I worked in a shipyard building destroyers.
I was working in a compartment with nothing in it and no door but I had the wrong security clearance so I was told to get out until I got the right security clearance.
About an hour or two late my ID badge had been changed and I could enter the compartment with no door and nothing in it.
Our SCIF always shouted “UNCLEAN!!!”
One NCO had a leper bell to ring...