/diy/ - Do It Yourself

I found this small handheld toy in the back of a drawer. You have a choice of three buttons to press that make a loud SFX - an explosion, a gunshot, and a ray gun zap. Looking inside it's a really simple layout. There's a speaker and a small board with mostly nothing on it.

I'm only an electrician novice, but I have a question: is it possible to repurpose this toy to play a different SFX somehow? What is the process of doing this? The little chip is hidden underneath some black tar crap on the board. But what is the basic process of flashing a SFX to a new chip, or rewriting the existing chip? How is it done?

Any information is very appreciated.