A job that requires absolutely no skill or talent, except for a complete lack of self-respect. Usually the kind of job one seeks after being fired from distributing flyers for a porno theater.
The term is derived from an episode from The Simpsons where Mr. Smithers, desperate for a job after being fired by Mr. Burns, inquires after a Help Wanted sign at Moe's. The job is pretty simple: distract Barney Gumbel until the midnight beer delivery is safely transacted. According to Homer, it's a job that many of them have only contemplated in the darkest moments of their lives.
Bill: Yo, how'd the job hunt go?
Evan: Terrible. I had to take an internship to a fishmonger.
Bill: Man, that's a Barney-guarding job.
Evan: I know. I think I'm going to bed. Don't bother me.