I wear sandals around the house but back when I was younger, we called them thongs. I remember Pops mentioning zoris when I was a teen but I can’t remember if the context was that that was what they called them when he was a kid or that some people called them that. He grew up in Detroit.
I’m pretty sure that I became aware of the term “flip-flop” through Jimmy Buffet’s song Margaritaville, so late '70’s or thereabouts.