In my opinion, (and neither of these made it onto that list of 100, but they are fair dinkum SHOCKERS!) the worst movies I have seen are 'Dreamcatcher', and a movie called 'Chicken Park'.
'Dreamcatcher' is the only movie I have ever even considered walking out of, and if not for the fact I just had to see how bad it got, me and my mates would've walked out after 40mins and asked for our money back. Who woulda guessed the genius was in fact a friendly alien who could get rid of those evil aliens that looked like turds? Hmmm ....
'Chicken Park' is supposed to be a comedic piss-take of 'Jurassic Park'. 30ft tall chickens being the joke. This movie was NOT worth the $10 I paid for it. You get comedy movies that are genuinely funny. You get comedy movies that are not funny (but are supposed to be). You get comedy movies that are supposed to be funny, but are that tragically unfunny, they become kinda funny again due to their stupidity. 'Chicken Park' rates another notch or two below that. This movie is so bad that you cringe all the way through it, and constantly say to yourself "Oh my God" as you shake your head in disgust and shame. I only watched it once, and I will never be watching it again. I only keep it to remind myself that I should never again buy a cheap, unknown movie on impulse based on the text on the back of the cover.