Two options, one mainstream and one art house:
The Lawnmower Man
When Steven King launches a lawsuit to have his name excised from all publicity for a movie based on his book, that ought to be fair warning. But I saw it anyway. The worst 'mainstream' movie I have ever sat through. Usually the trashiest movie at least meets certain minimum standards of entertainment - you can usually laugh at the movie if nothing else.
I am unable to comment on "The Lawnmower Man 2" as my temporary insanity had passed by the time they released that particular turkey. It may have been worse than the original, for all I know. AFAIK the space-time continuum is still intact, so that does seem unlikely.
That last remark just reminded me - page five and no-one has mentioned William Shatner yet?
Butterfly Kiss
LM was bad, but at least it had Hollywood production values, sort-of. Butterfly Kiss was a piece of British arty garbage. The intelluctual power can be deduced from the names of the two main characters - Eunice, and Mimi (I think - I try to forget). The point was that they used nicknames - "You" and "Me" - I bet they burned the midnight oil coming up with that piece of genius. I don't think I've ever cared so little about any characters, ever. I diodn't hate them - that would have required some form of emotional connection. I genuinely did not care one iota about anything in the movie.
What I did care about was finding the colleague who had arranged the trip to see this (and then mysteriously failed to show up). After about 10 minutes we were convinced we were victims of some monstrous practical joke. When the torture eventually ended we found he had turned up, and had genuinely thought the movie would be entertaining. Strangely enough, I never saw another movie on his recommendation.