A Sailor's Tongue

Even long before humanity sailed the stars, on Starships plowing through the Hypersea, back when just one world was within grasp, sailors were a superstitious bunch. And with a vastness of darkness surrounding them, they found their fears and hopes again. So while they developed linguae francae to communicate with each other, they also developed new superstitions, as well as words to describe them with.
A few examples are listed below, but there are more superstitions than there are ships, and more Stormfarers that believe in them, than there are stars within our grasp.

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Keep a corner of your eye on that

Looking straight at the dark areas of the hypersea is enough to drive one mad. If one stares into the abyss long enough, it will never leave one's mind. But at the same time, one cannot afford to just look away. That way, all that happens is one will get caught by surprise when something does go wrong. Thus, the expression tells you to keep a corner of your eye on that. It applies to any situation or individual that you don't fully trust, so you look carefully but subtly.

Some fools die quick. Some do not die quick enough.

There are those that do stupid things and quickly pay a price for it. It's still better that end up having others pay the price instead. So, it's better if a fool dies quickly and only takes themself out, rather than dragging others to the grave instead.

A damned Boatswoon if ever I saw one

Bosuns, also called Boatswains, are essential to the safety of a Starship. They command a lot of the crew, so many try to stay on their good side. At the same time, some take that too far, just agreeing to everything. Asides from the contempt this rightfully gets from other sailors, it also is dangerous. A Boatswain needs to know what's going on, to prevent problems from arising. Someone who merely swoons over the Boatswain, rather than actually stand up against them if needed, will only prevent the Boatswain from truly understanding how well everything is going. And a mistake missed that way, could easily be the end of an entire ship and crew.