The mission of this day is to create an international day to celebrate Australia's national icon. Red Kangaroos

Monkey Day celebrates monkeys and "all things simian", including other non-human primates such as apes, tarsiers, and lemurs. Monkey Day is celebrated worldwide and often also known as World Monkey […]

The name speaks for itself.  However, it's origin is a bit sketchy. Zoos I've written about in 2024.