This is an adjectival expression best used to describe people, places, things, moments, and events that are so annoying/stupid/ridiculous/grating that patience diminishes, moods deflate, and the threat of violence increases. Basically, this phrase can be used to describe anything or anyone that grates on your last nerve.
The fact that we are having a departmental meeting to discuss cover sheets and TPS reports really makes my ass hurt.
Homie 1: Yo last night was crazy bro.
Homie 2: Yeah man I barely remember anything.
Homie 3: Yeah we gotta go home now man.
Homie 4: Why are we all sleeping in the same bed?
Homie 2: It doesn't matter bro.
Homie 3: Why does my ass hurt?
Homie 1: It's nothing man.
Homie 1 Had total recollection and was actually the one who had a fivesome with the homies