Two come to mind, and both were in situations where I would have seen another movie if I could. The first was the 1987 movie Hunk(I'd be surprised if anybody else has heard of it), and the reason why I saw it instead of another movie was that a friend and I were at a shopping center with 3 theaters and we wanted to see a movie. The other two were rated R and we were underage, so Hunk(rated PG) was the only movie we could see. It was a comedy but it was stupid and one of the worst movies I've ever seen.
The other was the 1992 movie Night and the City, which starred well-known actors Robert DeNiro and Jessica Lange. The only reason why I saw it was because I had intended to go to a midnight showing of Bram Stoker's Dracula on the night it premiered at the same theater multiplex. However, the tickets sold out just before we got to the theater, and since I and the two other people I was with had planned to go to a movie, we decided to go to Night and the City because it was the only other movie showing at the same time. It was one of the most boring movies I have ever seen. I fell asleep at some point during the movie, so I don't even remember much about it, except that it was boring.