Help with finding app

[popcornmonster]

So my friend has a little brother. When she clicked a button on the little brother's mac a gif of a doge came out and a bunch of text just started popping up. I don't know if it's an app or a something I can manually create but I would appreciate if someone knew how I can make it. It seemed really interesting and I want to see what I can do with it.

Thanks <3

 

[Rok73]

Asking your friend is not an option?