Click the green flag, sit back, enjoy. Please check out the 600+ nice remixes made by other scratchers: https://scratch.mit.edu/studios/27457559/ And of course, feel free to remix yourself!
The fireworks idea is all @minguma's. I just added a large transparent circle to the costume (to allow the sprite to go off-screen) and sound effects, and also changed the code a bit. The fireworks sound effects are from https://www.fesliyanstudios.com