“Happy endings are bullshit,” says Willie T. Stokes (Billy Bob Thornton) at the beginning of “Bad Santa 2,” and don’t we know it. A disheveled, alcoholic, womanizing criminal in a Santa suit may be just the face to epitomize our troubled times, but that doesn’t justify this thinly conceived sequel to 2003’s delightfully mean-spirited black comedy, which plays like an idiot fan tribute to the original.

Trading brains for repetition, “Bad Santa 2” rejects the ambiguous finale of the first installment, which left viewers wondering if the giddy happy ending was real or imagined. Did Willie die? Go to jail? Or actually find some modicum of domestic bliss? Directed by Terry Zwigoff from a wry script by Glenn Requa and John Ficarra — based on an original idea floated by the Coen brothers — “Bad Santa” existed within the bad vibes of its obnoxious antihero; you could even feel sorry for him.