sapiens

Generally, if you find a post offensive, report it. There's a button on the left.

That said, I hate most of the things that other people have already mentioned.

I hate it when people sit behind me and complain about me obscuring their vision. (I'm tall). I show up to the theater 15 minutes+ early in order to select a seat I like, without people behind me. If you want a good seat, come early.

I hate people who come into the theater after the movie has already begun and ask me if the seats next to me are taken, interrupting the movie.

I hate friends who ask me to save a seat for them at a new movie and then show up late.

I hate people who save more than 1 seat for others (and the "others" are not currently in the movie theater).

I hate people who have not taught their children how to properly behave in a theater. I'm a parent. You're making the rest of us look bad.

I hate people that bring children to movies that are inappropriate for them to see.
I don't mind people bringing babies to movies as long as the baby is quiet. (Though wouldn't loud, violent, noises be upsetting to a baby?).