On the surprisingly-entertaining A&E reality show "Airline," a man was actually arrested because he (a) was wearing an NYPD t-shirt, (b) was feigning vigilant behavior on the plane, and (b) insisted to other passengers that he had to have access to the aisle so he could see what was going on.
As I recall, he was charged with "impersonating an LEO."
Please don't end up like that guy.
No worries. I know the difference. I don't really try to cross the thin blue line, and I have never claimed otherwise. Still it's fun.