Walked out of Apocalypse Now as a teenager, just hated it.
Life of Pi - I spent the entire film wanting the tiger to just eat the boy and make it end (I am aware it was all an allegory, that did not make it less boring).
Babylon - it is just an astonishingly bad film that wasted the talents of its cats.
Finally, Alvin and the Chipmunks 2, which for some reason I had to see twice in the cinema, possibly because one of the DC decided they loved it so much they went back with friends for their birthday.