It was something by Heidegger, probably Being and Time. (By the way, Sartre is real bad reading too.)
Lots of good nominations on this thread already, though I enjoyed Atlas Shrugged and Proust was ok. Pynchon (Gravity's Rainbow), that was an ordeal for me. But so was Jonathan Livingston Seagull.
Some trash is unavoidable. Into each life, you know. Somebody gives you a book they swear is riveting and life-altering, and you keep reading and hoping there's a point, or something's bound to happen after 400 pages.
I counsel my children to beware of paperback books that come in different colors, like Kleenex. If the cover's decorative that's a dead giveaway of a book that reads like disposable wipes.
Finally got to where I could read that monster. Comes down to Plato's Timaeus' kineton tina aioonos poiesai.