Twilight will take the title because it is the only movie I have ever walked out on. I didn't even wonder how it ended up.
Was at the Morale Welfare and Recreation Center at the Navy base. Being a large base, it had a small movie theater. Free movies for everyone, cool deal, yadda yadda yadda. Saw Twilight was playing. This was at the peak of the initial popularity so I decided to see what so many people were gushing or ranting about.
About the time the vegetarian vampires started playing super-jump baseball, I walked out.
Miami Vice was a close second. The only thing that kept me from walking out was my friend wanting to stay and find out what happens. I still regret not walking out.