Old, crusty, or worn out.
"Look at that old bag o' bones over there. She's really festered out."
Broken down; out of commission, on the fritz.
"What happened to your
car Sally? Oh, it's festered out again. I think my hubcaps are
bad."
What happens to a large pimple with a big white head that grows in the middle of your back that you can't get to.
"
Dan what the
hell's that on your back? It's all festered out."
"
Tish used to be a good lay in the
sack, but now that everybody's had a
jab at it, she's all festered out."