I was brought up to say what/lavatory or loo/napkin etc, and anything non-u was frowned upon, but I later spent lots of time living overseas with English-speakers from elsewhere so have drifted into saying toilet and living room sometimes.
DP is several notches posher than me (titled relatives, actual stately homes etc), and he winces at 'toilet' or 'underwear' and calls it a 'drawing room', so I deliberately use the non-u words to tease him occasionally, as he is very aware of how arbitrary and stupid it all is. But I could not bring myself to say pardon, even as a joke...
English class-based language is weird and fascinating but really should not be taken seriously.