Every culture has its quirks. Athletes wear lucky socks, performers won’t whistle backstage, and sailors—well, sailors have coffee mugs that never, ever see soap. If you’ve ever stepped into a Navy chief’s mess, you’ll notice a strange phenomenon: mugs stained nearly black inside, chipped around the rim, sometimes with “DO NOT WASH” scrawled across them in bold Sharpie.
It isn’t laziness. It isn’t neglect. It’s tradition. And in the Navy, tradition is everything.
The Dirtier the Mug, the Stronger the Sailor
In Navy culture, a coffee mug is more than just a vessel for caffeine. It’s a badge of honor.
A brand-new Sailor with a squeaky-clean mug will often earn side-eye from seasoned chiefs, who see a glossy white cup as a mark of inexperience. The older and dirtier the mug, the more “salty” the Sailor.
Inside those mugs, layers of coffee residue build up over weeks, months—even years. What starts as staining eventually turns into a thick patina that Sailors wear proudly, the way a warrior might display battle scars.
Some swear the mug even improves the flavor of their coffee, like a well-seasoned cast-iron skillet.
A Story Passed Down at Sea
Sarah Sicard, a reporter for Navy Times, shared a perfect example of this tradition. Early in her career, she worked in an office alongside a Navy Veteran who kept a battered old coffee mug on his desk. On the side was a taped-up note that read:
“Don’t wash me.”
When Sicard asked about it, the Veteran laughed and explained it was a habit he picked up at sea. After years of drinking nothing but black coffee, the residue inside his mug had become a part of the ritual—so much so that he actually enjoyed the taste of what he jokingly called the “seasoning.”
To outsiders, that may sound gross. But to Sailors, it’s a symbol of pride.
But Wait… Isn’t That Gross?
Here’s the surprising part: it’s not actually as unsanitary as it looks.
According to Dr. Jeffery Starke, an infectious disease expert at Baylor College of Medicine, reusing your own dirty mug isn’t dangerous.
Viruses and bacteria don’t survive long outside the body, and it’s very difficult to reinfect yourself with a cold or flu.
As long as you’re drinking black coffee—the Navy way—you’re safe. Cream and sugar, on the other hand, are a mold factory. Leave a sweetened coffee sitting in your unwashed mug for too long, and yes, things will start to grow that even the toughest chief won’t want to drink.
But stick to the strong, bitter stuff? You’re golden.
In fact, from a purely hygienic standpoint, a single mug that only you use is often cleaner than a communal cup that gets washed and shared around.
More Than Coffee
For Sailors, the mug is personal property, superstition, and identity all wrapped into one. A chief’s unwashed mug tells the story of long watches, endless cups of joe, and countless days at sea.
It says: I’ve been here a while. I’ve earned this.
Sure, it may look grimy to an outsider, but to those in the Navy, it’s just another one of those time-honored traditions—like painting a ship’s keel before a launch or ringing the bell at a change of command. It’s messy, it’s a little weird, and it’s definitely not going anywhere.
So the next time you see a Navy mug with a note that says “Don’t wash me,” take the advice literally. That stained, blackened cup isn’t dirty—it’s seasoned with pride, history, and a whole lot of caffeine.
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