'Their' language hasn't really changed that much apart from the obvious lean towards 'Gangsta' .At least it hasn't since I were a young 'un in the 70s.I think it is times rather than language that has changed and words that were 'bad' language or 'swearing' 60 years ago are now just regular words.
When I was a lad certain words were not used in front of mum/nan or female family members in general but were OK with dad/grandad/uncles etc.My Nan called it 'Pit' language.In our house there were two 4 letter words not to be used in front of mum and one that was completely unacceptable to use at all.