Acronym Dictionary

[JoeCB]

The one that I find stumps most folks is , POSH  (port outbound- starboard home).

if you are up on your Victorian history you should know the origin of this one...

Joe B

[Branson]

I've heard that, but it still sounds like a folk etymology to me.  I'd like to see some real evidence.  If it really did originate in the Victorian era, it is remarkable that it didn't make it into the Oxford English Dictionary.  Just checked, and the only "posh" in the OED means broken into parts.

The Oxford Universal Dictionary (later publication than my copy of the OED)  gives it's  earliest written example as 1918, as a slang word for money.  That puts it, essentially, into the Vulgar or Canting vocabulary, where it could be some vestige of English rhyming slang.