A person at company who has been deemed worthless in terms of how they contribute to the company but still continues to hold a job. That person is thought to be performing oral sexual favors in return for keeping their job.
John: WTF does Gary do around here?
Pete: Dude, he's an office goblin.
John: You mean office ghost
Pete: Nope, office goblin. He's got to be gobblin' somebody if he's still working here.
John: Yeah, you're right.