Phat back is a term used to describe a morbidly obese rear end....That's a slight exaggeration.
A phat back is a big-arse bum.
Joleon Jochum: "Damn, Mac, that's one Phat Back,"
Mac: "Thanks, I get it from my gran,"
Joelon: "The one I shagged last week?"
Mac: "Nooooo, the one with 1 boob - right in the middle."
Joleon: "Hahaha, one boob?"
Mac:"...She had breast cancer."
An individual who attempts to seem more progressive-than-thou by advocating for popular issues-of-the-month without creating any real or lasting change for those they are supposedly advocating for. These people can be identified by a combination of factors including upper-middle class income, Che Guevara T-shirts, peace sign bumper stickers being placed next to their Free Mumia and Obama '08 stickers on the back of their Honda Civic, and a medley of other products created by the terrible capitalist market they vow never to support.
Patback Liberal: We need to help Native Americans by changing the mascot of the Washington Redskins to something less offensive and more loving. I'm tolerant.
Smart-Ass Student: This is just another way for white liberals to pat themselves on the back and pretend they did something useful.
Patback Liberal: Check your privilege! Image is important! In case you didn't know, I'm 1/32nd Cherokee you racist misogynist pig!