So many incidences of musical "shock of the new", I hardly know where to start.
I was brought up on a diet of my parents' musical taste, so mostly '50s rock 'n' roll and pop, and some '60s stuff such as The Stones, The Grateful Dead and The Beach Boys.
My first real shock, though, was "Metal Guru" (Marc Bolan & T.Rex) in '72, because it was the first time I realised that lyrics didn't need to be profound, meaningful or even narrative to be enjoyable.