"Trout Mask Replica" by Captain Beefheart & the Magic Band. I often saw it on those "Best Album of All Time" lists that are published in rock magazines, along with classic albums by the great old artists (Rolling Stones, Springsteen, Dylan, etc.), so I bought it. Well, it turned out to be one of the worst albums I've ever heard, a load of really bad "avant garde" nonsense. A fucking big waste of money.