system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is "cheese" the go to word before taking a picture?
gpt
Because the "ee" in the word makes it look as if you smile. Try it. 
By saying "chEEEEEse" for a longer time, you can get all people in the picture to laugh 'naturally' for a short while. But not only "cheese" can be used, any word with a long "ee"-tune can be used. Cheese is just very simple and known by almost everyone.