This is just so clever, and completely hilarious. Check out the link! Singing sock puppet. Apparently, someone repurposed a singing card to be used as the mouth of the sock puppet. I have made something similar in the past and posted it. I did not use a singing card but I think I'm gonna have to now. This is just too cute! My guess, not a toy for young children though. They would most likely rip it apart, and the singing sock would cease to be.
Check out the link that tells you how they did it. Here!!!