[Miss Olivia]

I don't think I can pick just one.

Boogeyman sucked, but so did
Darkness Falls
The Fog remake (I actually got pissed off I bought it, and that almost never happens to me)

Breeders
Metamorphosis: The Alien Factor
Troll 2
Carrie 2
Sleepwalkers
Rose Red
Various assorted Leprechaun movies
White Noise
They
Those are the ones off the top of my head.
Now keep in mind these are all movies that I would never watch again, once or twice being enough. I know there are a lot of other terrible movies out there, but a lot of the lower budget ones at least entertain me, like Troma video and crap like Jack Frost. The movies I listed were not only bad, they bored the hell out of me and left me feeling unentertained.
Different strokes for different folks.