Shart art is when you defecate in your trousers without much fair warning (shart), then create art with your own feces. To many people, it is a very cherished hobby. People generally finger paint with their feces as a form of shart art, but there have been some situations when people had made sculptures and even houses.
Person 1: "Dude... I just sharted. Gross..."
Person 2: " Dude awesome! Now you can make shart art with it!"
Person 1: "That sounds amazing!" (starts playing with feces) "This is fun!"
Person 2: "you know it is..."