The general attitude of a fat person. Your sterotypical person with a fatatude would be: fat, obnoxious, full of themselves, and loud. Often they are women, and often these women have stomachs that stick out further than their boobs. People with fatatudes often carry food with them at all times.
Ben: Dude, that bitch has a serious fatatude.
Jason: Yeah man, she really needs to stop piggin out.
"Mary has serious fatatude problems. Maybe she should lose some weight."