Combine the nursery rhymes and poems they know, with the poop talk they love. Simply ask Alexa to play a poop poem, and a random one will be chosen each time.
I dedicate this to my four year old son, who finds anything poop related to be the most funny thing in the world. He has just gotten old enough to converse with Alexa, but I found most skills to be overly complex for a 3-4 year old. If your kid loves poop, get ready for hours... well, let's hope for at least minutes, of entertainment.