A few years ago I accompanied a friend to a talk by an academic historian, for other academic historians, about the period between the world wars. The presenter

A few years ago I accompanied a friend to a talk by an academic historian, for other academic historians, about the period between the world wars. The presenter made a joke like "it's hard to say when precisely world war 2 broke out, but we know world war 3 began in 1914." It took me a minute to get it but the audience responded very well! There was professionally appropriate chortling but a lot of nodding also.