Short for 六一国际儿童节 (International Children's Day, June 1). Celebrated in China since 1950; primary schools typically hold performances and kids get the day off or light classes. Adults often joke 过六一 on social media - a tongue-in-cheek claim to youth.
usage
The name-by-date pattern is very common in Chinese holidays: 五一 (May 1), 六一 (June 1), 七一 (July 1, Party founding), 八一 (Aug 1, PLA founding), 十一 (Oct 1, National Day). Read as digit-digit, not as a number.
