1. Exclamation used to indicate disgust in one's excessively lazy lifestyle.
2. Adjective used to describe a person who is habitually excessive, particularly in relation to food and drink, but also in relation to drugs, lethargy, and general sloth.
"Don't get to close to Vincent's flabnasty mom. She'll chew your arm off! Flabnasty!"
"Woah that story is pretty cool but I'm a little flabacertatuaxious. Explain it a little more and keep the story going it sounds amazing I wanna hear more."