How to play a kazoo???????

im very sick and i cant do anything that requires getting out of bed and im not feeling too well to play my guitar or piano so my sister bought me a kazoo. im just sitting here trying to make it work but the dam.n thing wont work! i keep humming and stuff and i tried saying "who" but i just cant do it my sister tried it on the one sihe bought for herself and she did it but why cant i make that sound whats wrong with me?!