A busking day is when people who like to make music or perform on the streets go to a certain place and show off their talents. Imagine going to a park where lots of people are playing music or singing or doing tricks like juggling or magic. These people aren't getting paid to perform, but instead they rely on the people who like their performance to give them some money if they want to. Think of it like giving someone a present for doing something really cool that you liked. So a busking day is when lots of these performers come together in one place and people can watch and enjoy the different performances. Plus, it's a good way for the performers to practice and get better at what they do!