I read a book once where this guy was reminiscing about his childhood in the 1920s. He mentioned the summer when his sisters and their friends were caught up in the tie-dye rage, which “produced handkerchiefs of unbelievable ugliness.”
Weed. Again, something that dates back to the 1920s, if not earlier, but didn’t come into widespread use until the 1960s.
I would say “Non-contact dancing,” but that started in the early '60s, with the Twist.
Sesame Street, Mister Rogers Neighborhood, and similar academically/socially educational shows for children. (I know, Mr. Rogers’ show started earlier, but it only became nationally broadcast on PBS in the late sixties.) From these beginnings, though, came all manner of similar television programming for children: From “The Electric Company” and “Schoolhouse Rock” to “Dragon Tales” and “Dora the Explorer” and so forth…
Sure, there had been any number of television shows aimed at children long before the late sixties, but I think that Jim Henson and Fred Rogers pretty much started the trend of using the TV to actually teach children social and academic information.