1. To be completely burnt out and fed up with your job. 2. To be in a position that definition 1 can apply to you.
Coined from a Seattle based software development product manager that started as clean cut guy in a suit and left as a strung out excuse for a human with stains on his dirty hoodie that hadn't showered in a week, all within 6 months.
"Lay off the new guy, you're gonna Sweeney him."
"Dude, dya here about Nick getting Sweeney'd? He quit his job, moved to Bolivia and is now raising Chinchilla's for their fur. But he's in a better place."