If those are the most prominent things you find for that abbreviation, I have to start doubting Wikipedia. As a German seeing that abbreviation so freely used is always a little bit shocking.
I always thought it stood for "Set Sail", but this definition is more pragmatic.
Memories can be odd, and I assume everyone has a similar story of some early situation.
(Officially USSS, but it's often abbreviated to SS in common parlance.)