When one farts and considers it to be art.
2: Ew! What was that?
3: Well, it was just art.
Generally speaking, the term 'Fart Art' relates to the abstract contemporary art formed by the human arse at its most creative - usually involves brown, green or yellow paint of entirely organic origin, combined with an explosive, resonant fart. Fart Art is not often on public display, but common galleries for this particar form of artwork tend to be the inside of bog bowls or discarded underwear. Most Fart Artists are male for some obscure reason, although occasionally fart artisans of the female variety can be found amongst the ranks of students.
"I just got over a bout of dyssentry, but duuude! Did I blow some fart art!"
When an artist inserts several colored paints into his/her rectum, then proceeds to fart it onto a canvas.
Guy 1: Dude, check out my fart art!
Guy 2: Not bad, but it smells awful!