What does Atlassian mean by having a FedEx day?

The software company Atlassian injects a BURST of AUTONOMY into its workplace by setting aside a day each quarter when employees can work on any project they choose , however they want with whomever they like.

This is a masterclass in explaining how intrinsic motivation can help encourage innovation and creativity in modern day workplaces.

This concept can be extended to schools as well as explained by Daniel Pink in his book Drive