A toy that's been through multiple full national revival cycles since the 1920s — and is still sold new today.
Duncan Yo-Yo (1920s) was a genuine nationwide craze decades before "going viral" was a phrase — and it's still made and sold today. This is a genuine pre-internet product — a real, nationwide sales phenomenon decades before social media existed, spread by nothing but word of mouth, in-store demonstration, and traditional advertising. Many of these are still in production today, largely unchanged.
The modern yo-yo traces to Pedro Flores, a Filino immigrant who founded a yo-yo company in California in the 1920s; Donald Duncan later bought the rights and built the brand into a household name.
Duncan drove huge sales spikes through traveling contest demonstrators and national TV advertising in the 1960s — a pre-internet version of an influencer campaign — and competitive yo-yoing still has an active global circuit today.