A combination of severe laziness, arrogance and mental retardation which means the root cause of ones obesity will never be fully addressed or rectified.
Weighing 300lbs and having the fattitude to telephone your non-obese partner to provide a beer delivery service direct to your sofa/bed, rather than get off your fat arse and risk burning calories.
Destroying several sofas by the sheer mass of ones arse and then blaming the manufacturer, rather than your own fattitude.
or a small or skinny person acts as though he/she is fat
jeb: man she's so skinny where does it all go.
carl: ya she definatley has a fattitude.
jeb: yesterday this fat chick was giving me fattitude.
carl: i hate that.