Who would have thought it was bad luck to give a sailor water?

According to the U.S. Navy Mess Night Manual, published in 1986, there are several serious aspects of dining etiquette that sailors should adhere to, with an entire section dedicated to toasts. While some rules are logical at first glance — foreign heads of state drink first, regular members of the navy last — others might leave you feeling lost at sea.

Traditionally, toasts are made with Champagne or port, but other wines are fine. On the other hand, toasting with water and other non-alcoholic drinks is highly discouraged. “Although civilian practice is more permissive, in the military, toasts are never drunk with liqueurs, soft drinks, or water,” states the manual. “Tradition is that the object of a toast with water will die by drowning.”

While odd, this superstition has roots. In Ancient Greek mythology, the dead would drink from the River Lethe in the underworld to forget about their lives above. Thus, as a symbol of their transition, the Greeks would offer a toast with water in their glasses to send off their dead. So when toasting someone with water in your glass, it’s as though you are wishing bad luck or worse, death, upon them.

The manual also includes another toast-related snippet of military history. In 1649, during the Royal Exile in England, officers that were still loyal to the uncrowned King James I passed their wine glasses over their water goblets, subtly saluting their king who was “over the water,” meaning he was in continental Europe. When this ruse was discovered by military officials, water goblets were removed entirely from banquets and celebrations.

So if water and soft drinks are disapproved of in the mess hall, then what is the ideal NA option?

According to the manual, abstainers are advised to fake it until they make it. “It is socially improper to refuse to participate in a toast, even though one does not drink,” the manual says. “A non-drinker should lift his glass of wine to his lips without actually drinking it.