CRAB
Well us 'fish'eds' have been at this aviation game for 100 years now (not me personally you understand) so I feel it encumbant upon me to continue educating our junior service colleagues. If you want to know about aviation ask a sailor.
Google has it's purposes but I actually learnt about that little saying on the BBC Radio 4 programme 'Quote, Unquote' many moons ago. Until then I too imagined shipwrights with little pots of tar dabbing the wounds of beached wooden warships.
G.