There are, as you might imagine, a lot of different drills and exercises in the Navy. The ones that are done for scoring against (or by) the ship have letter and number designations that correlate to some scheme that I have long since forgotten.
One sticks with me: Zulu-5-Oscar. A Z-5-O is a shipboard security drill in which a person who is not a member of the ship's company tries to get aboard and roam around the ship unescorted. Most of the the time, the drill is successful from the ship's perspective in that the person trying to get on board is caught.
This is no shit:
There was one Command Duty Officer who got the word that a Z-5-O was going to be run against his ship on his duty day by another ship. He corralled a young sailor from that ship and sent him back with this word: "I've had enough of this shit. I'm gonna sit by the Quarterdeck with a shotgun and I'm gonna shoot the fucker who tries to pull a Zulu-Five-Oscar on me."
The CDO ordered the duty gunner's mate to give him a shotgun and he sat on the fantail's capstan, right by the Quarterdeck. Sure enough, about 90 minutes later, a nervous looking sailor walked about halfway up the gangway, threw his hands high over his head and screamed: "Zulu-Five-Oscar! You caught me! Don't shoot!"
Again, one ship was tasked with trying to run a Z-5-O on another. A lieutenant (JG) volunteered to do it. He went to the uniform shop and purchased a set of shoulder boards for the summer white uniform. The shoulder boards were for a lieutenant in the Chaplain Corps. He put those and a briefcase with some religious literature in his car. The day of the Z-5-O, he went out to his car, switched his shoulder boards to the chaplain's ones, picked up his briefcase, and walked to the ship he was assigned to run the drill on. Once he got on board, he told the OOD that he was Chaplain O'Hara from the destroyer squadron.
If the quarterdeck watch had been on the ball, they would have noticed that his ID card was for a LTJG of a different name. They would have noticed that there was no Chaplain O'Hara on the Desron access list. What they did do is call the XO and tell him that Chaplain O'Hara was there from the Squadron. The XO told them to send the chaplain to the wardroom, so they gave him an unescorted visitor's badge and let him go.
And so he did. He wandered to the wardroom, tucking a few 3x5 cards behind cable runs (the cards read "BOMB") on his way. He told the XO that he had been transferred in six weeks ago and was making his rounds of all of the ships. He chatted up the XO for about fifteen minutes, then the XO called the Captain to let him know that the new squadron chaplain was onboard and asked if the Captain could see him.
The Captain could. The Captain did. And the Captain had a lot on his mind that was troubling him and he talked some of it out with Chaplain O'Hara. "Chaplain O'Hara" at this point was terrified, as this had gone well past the fun he had expected to have had. He heard the Captain out, then made his excuses, saying he had a meeting back at the Desron. He left the ship, went back to his car, put on the correct shoulder boards and then went to report to his XO.
The XO called the other XO and asked: "I heard you met Chaplain O'Hara" ...... "Nice kid, eh?" .... "Did you know he was a Zulu-5-Oscar?" The XO could hear the other XO screaming and he didn't need a telephone.
Nothing was really ever done to that ship, the embarrassment around the waterfront was enough punishment. "O'Hara's" CO congratulated him on a job well done and added that if he ever said a word about what the other Captain had told him, that "O'Hara" could expect to spend the next year counting penguins at McMurdo Sound and the following four years handing out basketballs at Adak.
"O'Hara" kept his mouth shut.