For additional reference...

Space Shuttle Door Gunner

A humorous reference to rear echelon personnel (air force) who like to talk up how much combat experience they have.
A humorous term for an "armchair commando:" one who likely did not serve in the military yet insists they did highly unbelievable things in the military.
An internet blowhard, especially on internet gun or military forums, who like to dog others from the safety of theor anonymous keyboards.
and SSDG

Same Shit Different Guy, or alternately, Same Shit Different Girl;