With the costs of going to the movies these day I can't afford to leave mid way.
Amen to that. I inadvertently went to see Raja [I think
this one, but the plot summary doesn't match what I remember of it] (getting it confused with
Beyond Rangoon, which in the end I never saw), which is a Bollywood film. I was ethnically unique in the audience, not least because it was not in English, or sub-titled so I couldn't understand the dialogue. I like to think I pick up plots quickly, so stayed, since I'd paid.
To answer the original question, I've walked out of a few films:
A Knight's Tale,
Rules of Attraction (both fairly near the beginning) and
American Pie: The Wedding (about 2/3 through - perhaps should have stayed it out).
I'm not a huge fan of horror, though tinker round the edges: the night I saw
Mary Shelley's Frankenstein in the end I decided I wasn't in the mood so walked out, though I saw it at another showing. Stood up to leave
Hostel, moved back a few rows, but in the end sat down and saw it through.
For variations on straight "walked out", during
The Mummy the reel snapped (irrecoverably for that time-slot) so we were evicted (though I went to see a subsequent showing); during
Mickey Blue Eyes a parent died (150 miles away, expectedly) so I missed a reel or so taking the phone-call and in
Shall We Dance (with wife) the 3rd reel was upside down and back to front (very amusing!) so we got our money back and had to go to a subsequent showing to see the rest.
(It's quite sad but I keep a list of all the films I've seen since 1995, including notes such as "walked out". One such note is that a friend & colleague was also in the auditorium to see
Final Destination 3, but walked out, only to find his car stereo had been stolen: double bad!)