Someone who is supposed to be a true expert at something but in reality is a pretentious, incompetent fuck up, usually at your expense and without any risks taken on their part. Their incompetence can be deliberate but is often unintentional. Either way, these douchebags could really give a rat's ass about how they've fucked up your situation. Wisdom I've learned from an old Sicilian.
This jamoco lawyer I've been dealing with was supposed to help me out, but instead screwed me out of hundreds of dollars and didn't do me a goddamned thing, except to empty my bank account.
That's right - keep escalating our troop levels in this unwinable war and continue killing us all, you fucking jamoco.