Indiana Jones and The Crystal Skull when Shia LeBeouf was swinging on the vines infront of a green screen with CG monkeys. That or the CG ants forming a ladder that or...Well, just about any of that CG in the movie was terrible.
Star Wars: Revenge of the Sith, when Padame and Anakin were having their exchange on the rooftop and it goes into the whole "Perhaps you're blinded by love." "No, no your beauty has blinded me!" Insert distinct what the hell coming from my lips.
Terminator: Salvation in the very first five minutes the worse line I've heard all Summer. "Wow, so that's what death tastes like."
Simpsons movie. Everyone was saying it's the best The Simpsons had been in years, but within first thirty minutes I realize it was just an hour and a half long terrible episode of the past few terrible seasons.
Spider-man 3, soon as we saw Parker turn "evil" by putting his hair down to one side and putting eyeliner on then his whole EVIL strut and his EVIL dancing (or his whole move his arms and it blows Gwen Stacy's hair). That and when he started crying on the bridge.
At the end of Saw IV and V when it had their big mindless "TWIST" ending.