See biscut

While this is 100% true, it didn't happen at sea. As a matter of fact, it happened in Holy Lock Scotland while the Boat was tied up along side the barge that was between the Tender and the floating dry dock.
It was early, 04:30 approximately, the first liberty launch back to the tender was that early for the tenders cooks and mess crew that either were 'lucky' enough to live in nearby Dunnoon, or like me, were trying to make it back to the Boat before quarters at 06:00 after a painfully successful night of debauchery and general drunkenness lest I be on report for being AWOL. 
It was, for Scotland, a beautiful November night. Nasty wind, cold as hell and rain and snow mix made for a picture perfect day ahead. So, I was inside the liberty shed at the end of the fairly long pier where they had some heat. Benches lined the walls and I was the sole person at the time. Which was good because I was in a bit of a state of pain. Eyes closed and dreading every sound, waiting to hear the liberty launch pull up to the pier... 
As I lay there in pain I hear the door open and in come two Marines who apparently hadn't even slowed their progress toward a disabling drunk an hour before, dressed in civvies and staggeringly drunk. They bounced off of every wall and opened the door with what sounded like a small explosive charge. 
Without opening my eyes I checked my own melon for exterior cranial damage as they proceeded to let the world in on their desperate crushing need of a urinal. 
Similarly a twinge to do the same came upon me, but knowing the state of these two, I chose to wait, even if it meant waiting until I was back on board. 
If there is one thing a sailor learns early in his obligation, it's that sailors and marines don't mix.
As they entered the head their loud and obnoxious voices continued the predictable pattern. 
Then I heard one of them speak in a some what more hushed tone, he was aobut to disclose a secret, I thought. My attention piqued and my ears began to hear the unmistakable sounds of the high pressure flow of urine as it attempted to chisel away at porcelain... and finally the question: " what will you give me if I take a bite out of this urinal cake?" 
The first thing out of my mouth was 'a mental exam', but I wasn't (thankfully) heard. 
The other marine laughed a bit and muttered an unintelligible sound. And then a loud Yuck! As they both departed the shack. 
I opend my eyes and looked around to see if maybe some one else had heard and maybe seen the deed. No one. 
My curiosity no in over drive, I had to make the trip in to the head now for two good reasons. 
As I approached the urinal I saw the unmistakable mouth shaped bite in a fairly well worn urinal cake! I began to look around the floor for the piece missing but it wasn't to be seen. 
When I went out side only seconds later the launch was loading and I couldn't tell who was who at that point. 
But ever since then, I can't eat cake that early in the morning.