What is Bitcoin Pizza Day on May $22$nd$?$

A day where people who have Bitcoin purchase pizza and take it to their place of work.

The day when a computer programmer paid $10,000$ Bitcoins for two pizzas in $2010.$

A day sponsored by Papa John's where you can pay for pizza using Bitcoin.

A phrase coined by Satoshi, used to celebrate the worldwide success of Bitcoin.

The day Vitalik compared Bitcoin's security to that of a soggy pizza.