When you fart very loudly and get a great sense of relief, as the pressure from the gut is released through a great fart.
Aah, that was fartastic, I can relax again now.
fart worthy; a situation so fantastic, it deserves a fart.
son: i won first place in hurdles!!
father: gee son, thats fartastic
a smell that is closely related to that of a nasty fart.
or a person that feels a bit gasy.
riding in the car:
"what is that smell? did you just fart?"
"what? fart? no not me."
" it smells fartastic"
"i had mexican food for lunch so i'm a bit fartastic right now."