In the US if you work for the US Goverment as full time government employee, you are paid on a pay scale designated as GS levels, with a GS-1* as the lowest and a GS 15 the highest.
One day on a flight we were handed off to a new ATC center. As my co-pilot was flying that leg I was handling the radio and the following conversation occured.
Little ol' me; "XXXX, Justice 113 is with you FL-350.
XXXX center; "Roger Justice 113, say level."
Little ol' me, not missing a beat; "GS-14."
* I've never heard of anyone being a GS 1.