This vicious black comedy starts at a bachelor party and ends in some circle of hell; the road that leads from one to the other is paved with the worst possible intentions and is frequently horrifyingly funny. The groom-to-be is Kyle (Jon Favreau), a regular guy ripe to be led astray; his fiancee is Laura (Cameron Diaz), whose perfect wedding-in-the-making is the engine that drives her life. Kyle's stag-party-throwing friends are fast-talking Boyd (Christian Slater), who's spent way too much time getting in touch with his inner Neanderthal; quiet Moore (Leland Orser); and sparring brothers Adam (Daniel Stern) and Michael (Jeremy Piven), respectively the mature family man and the boisterous ne'er-do-well. Their Vegas bachelor bash starts with drugs, liquor and general testosterone-fueled horsing around, and ends in the accidental death of a stripper (Carla Scott), which is bad enough before Boyd persuades them all to hide the body and pretend the whole thing never happened, but only gets worse after. Actor turned writer/director Peter Berg makes an astonishing debut: Mordant comedy is fiendishly difficult to pull off (the adage should go, "Dying is easy, black comedy is hard"), and Berg nails the slippery tone more regularly than many more experienced filmmakers. And frat-house hijinks notwithstanding, no one is spared Berg's withering gaze -- not disabled children, not supportive wives and certainly not Laura, whom Diaz plays as the demonic twin of her sunny bride-to-be in MY BEST FRIEND'S WEDDING. Cable junkies may recall last year's STAG, starring Andrew McCarthy and Kevin Dillon; it also told the tale of a bachelor party gone very, very wrong. But though the premises are similar, the execution couldn't be more different: In a world filled with crude movie sitcoms, Berg's bitter, worst-possible-case scenario really does stand alone.