ei-flyer
"the captain makes a joke that 99.9% of the human species understand is a joke" and therein lies the problem: accounting for the 0.1% that don't find it funny - which is their right. A more 'mature' crew member may not appreciate or even understand the nuances of modern vernacular which might, indeed, cause offence.
From previous posts on this matter, it would appear that both parties had 'form' and, as the buck does stop in the left-hand seat, I'd suggest that judgement and tact were not being appropriately displayed by the captain.