What I see when I look in the mirror
Me:*looks in mirror
Me:...
Me: *tears run down my face
Me:DAMN LOOK AT MY FATASS GAINING AN EXTRA COUPLE HUNDRED POUNDS AFTER EATING A COOKIE CRUMB
Before "Phat" - there was just "Fat"
A dry Public Service employee who was also a keen fawlty towers fan, moved the meaning sideways a little from just being overweight, To a slightly sarcastic meaning of Having a good ol' time.
"You boys look like you're having a fat time"