Pretty soon it's going to be letter-box format, analogue TV's (or at least their mention) that draw blank stares...
Here're a few:
Imperial weights and measures (Canada - I encounter this one already)
Audio cassettes (I had to show a 15 year old what a "Walkman" was! LP's are making a comeback, though)
Going to the movie theatre to watch a movie (as in, life before VCR's/DVD players)