If you don’t know how a kazoo sounds or looks like, check it here: Kazoo - Wikipedia.

The kazoo from this video sounds like a hybrid of a trumpet and a harmonica, some people say it sounds like a saxophone too.

I’m not sure how much after-processing is in it, but it sounds great to me.

An unusual hack is applied to the kazoo that involves covering one end with tape and using a newspaper-like material for the diaphragm. There are techniques to control the voice as well.

Here’s a video about how it works.