Oren,
don't you think Forrest Gump blows??? Or do you think "Gross Out" is worse?

I consider the following movies to be worse, much worse, than Forrest Gump:

Sweet Home Alabama (dripping with painful awfulness)
Team America: World Police (dear God, why?)
Master of Disguise (may be the worst all-time movie ever)
Dr. Seuss's How The Grinch Stole Christmas (Jim Carrey should've been flogged)
A.I. (long, drawn out, please God, make it stop)
Closer (hate Natalie Portman... HATE!)
Swimming Pool (pointless)
Bounce (yet another Affleck snoozer)

With the exception of Master of Disguise, which I saw about half of on video one excruciating evening before I was mercifully allowed to leave before choking on my own vomit, I saw every one of the aforementioned films in a theatre, and in each one I nearly walked out. About ten minutes into the movie Closer, I was begging the g/f, "Please, this movie sucks, please let's leave!"

Given another hour or two, I could rattle off a few more, I'm sure.