Gee whiz, is it Christmastime already? What's that? I'm sorry: It's hard to hear you over the sounds of cash registers clanging. Oh, what prompted Jay-Z and Linkin Park to unleash this ill-conceived collaboration upon the masses, you ask? Why, to milk their hardcore fans, of course. Because those are probably the only people who will buy this pile-up -- uh, mash-up. The disc comes as a result of an MTV-instigated affair (shocking, I know!) this past July titled Ultimate Mash-Ups. Needless to say, if it wasn't already, the mash-up phenomenon -- first heard by the likes of the Evolution Control Committee and made famous by DJ Z-Trip and, most recently, Dangermouse -- is now officially played out. An idea that once seemed so innovative and spontaneous now comes off as rote and calculating. Like schizophrenic conjoined twins doing karaoke, Collision Course is just that. So if you must mash this holiday season, take a Z-trip instead. And if you happen to pass this wreck along the way, keep moving, folks. There's nothing to see here.