meself, some of the old jokes have shifted meaning with time.
My grandfather would have understood 'lady' as referring to a prostitute or 'lady of the streets'. My children would assume the other meaning; a downgrading of 'the little woman' (as she was known in the past.
This is the case with many words used in the slang sense; they go in and out of popularity.
'Bum' or whatever is a bad example because so many other referrents are in wide usage wherever English is spoken. Mostly they are understood without the need for explanation.

BBC and "auntie"- In the 1930s the 'Beeb' issued a list of banned songs. Some types of songs were banned for no firm reason except whim. The English slang expression for a code of behaviour- "auntie knows best," referring to the older generation or a prissy aunt's opinions- was applied to the BBC and it stuck. At this time, they claim to ban no recorded songs (but I doubt this is 100% true).
----------------------------
In England, and supported by the Oxford English Dictionary, the word enquiry is almost universally used. In the U. S. (and mostly in Canada because of proximity), inquiry is the accepted spelling. (Perhaps this has been mentioned before).
----------------------------------
Has 'bumff' (spelling varies) spread to beautiful downtown Pittsburgh? First applied to tons of paper generated in the English civil service, it spread to Canada, and eventually to junk mail, etc. I have now heard Americans use it. Is it now widespread in the U. S. or very local?