Common slang umong military enlisted to salute an approaching person in uniform when uncertain of their rank. Better to be safe than sorry. More common with the NAVY as Chief Petty Officers have gold anchors on their collars and are often mistaken for gold oak leafs (signifying a Lieutenant Commander or Major).
Bill- "Don't look now, but here comes an officer"
Larry-"No, it looks like a Chief Petty Officer from here"
Bill-"When in doubt, whip it out. Better to be on the safe side then to ignore him if he was an officer".
-Having enough suspicion of a situation or event to the point where you have to investigate further to see if it was wrong or bogus (or BS).
-Hearing what seems like bullshit, and checking it out further.
"Tom said he couldn't come in today because he had an appointment."
"Hmm, that's funny. He didn't mention anything to me. When he gets back, I want to see his appointment slip to smell check his story."