The combination of the words fat and nasty. Mostly used to put down ugly girls or fat lesbians.
"DAMNNNNN!!! That is one fasty bitch!!"
When faced with an experience of immense failure causing others to roll on the floor laughing at you screaming the words "owned", "pwned", or "you suck".
Indicating that you are the best or unbeatable, mostly used after someone has been "Kerped" (read definition for Kerp)