Quite simply people enjoying themselves!
A group of beachgoers at Burleigh Head, Australia, 1938. Source
New Year's Eve Party, December 31, 1936, at the Theatre Royal, Sydney. Source
Ground crew of the Royal Naval Air Station in Greenock, Scotland, dressed as pirates. I've no idea why. c. 1945. Source
Saturday afternoon in a beer and juke joint, Mississippi, 1939. Source
Stepping out for a spring fashion parade, Sydney, 1938. Source
The actor Frank Leighton almost goes overboard on a picnic for performers of a stage production. I suppose this wasn't fun right at this moment but I'm sure everyone had a great laugh about it afterwards... and what on earth was he doing right beforehand for this to be possible? Sydney, 1937 Source