The act of viewing someone else's half-assmanship and finding oneself so moved to comment upon the splendidness of the half-assmanship that onemust utter an exclamation.
Someone who actively decides to do less than their best because either they don't care or they feel the task doesn't deserve the time it would take to do a good job.
"Joe, are you going to put much time into your progress report?"
"Naw, I'm gonna half-ass it, cause nobody will EVER read it anyways".