This is a really simple demo of a chatbot. To be really effective, it should be fleshed out with more random things the penguin can say to you, but it does demonstrate the mechanic and the use of lists well. The penguin learns from you, so it says back to you things that you've said to it.
This is an example from the book Scratch Programming in Easy Steps by Sean McManus. More info here: http://www.sean.co.uk/books/scratch-programming-in-easy-steps/index.shtm