Probably controvertial choices but at the cinema my worst experiences were Matrix Reloaded and Lost in Translation. Both were really hyped, and I was really keen for the Matrix sequel being a big Matrix fan, but came out of both films so bored Didn't help that after LiT I had a chinese takeaway and got the worst food poisining I've ever had - not a great evening all in all.
Definately the two movie tickets I would most want refunded.
I've watched a number of films that are terrible- The Stuff, Supernova, Mega Shark vs Giant Octopus, Shark Attack 3-the one where John Barrowman makes the most suprising sexual come on in history. All of these films know they are terrible though. They are so awful that they are actually entertaining.
As such Jerry Maguire is the worst film ever. It is absolutely and utterly unredeemably terrible. I want to skin the entire cast alive and dip them in salt, pausing only to remove Tom Cruise's eyes with a spoon.