Squeaky Mouse is a lightweight free tool which can play your chosen WAV file when a particular mouse button is clicked.
Why? It's perhaps useful feedback if you're not sure which button you've clicked. It could help with in-person demonstrations, as anyone nearby will be able to better understand what you're doing. Of course it's also a simple way to play a joke on/ annoy someone...
Whatever your motivation, Squeaky Mouse is simple to set up and use, with no adware or other complications.
The program supports left, right, middle, XButton1 and XButton2 click events. The default WAV files are speech samples of "left", "right", "middle" etc - so, left-click, a voice says "left", right-click, a voice says "right" - but you can change these to any other WAV file you like.
There's an option to launch the program along with Windows, if you need the sound all the time, but it can also be turned off in a click or two.
A quirky app, but it works as promised, and if you'd like your mouse buttons to make more than a click then Squeaky Mouse can make it happen.