Ok, I'll bite. My biggest pet peeve:
Giant people sitting right in front of little kids in a theater. Look, I know you can't help your size. But come on, if you see a family sitting there, just look behind you. Is it really that hard to sit in front of an adult so the child can still see? Every single time, it never fails. We will be seated waiting for the show, and children will sit in front of me and my husband and the tallest person in the family will sit right in front of my youngest daughter. Then we end up moving around which makes several rows back move around because we were all seated so that everyone could get as best of a view possible.
The best part is when the very tall person can't sit still. So usually I end up switching seats with my kids, and I get behind the tall person. Ok, no big deal. I will just lean over and watch from the side. Except I get the person that adjusts every 5 seconds during the show so I am getting whiplash just trying to watch clips of the show.
Again, I understand you are tall, but you know you are tall, so when there are multiple seats available, don't choose the one right in front of a child, and no joke, sit still or sit in the back.
My second place pet peeve:
Adults not only standing in the front so kids can't see, but then they put their children on their shoulders. So now NO ONE can see. I don't mind the iPads so much, cause, hey, I can still somewhat see through their screen. If you want your kid on your shoulders, get to the back of the crowd. To me, that is extremely selfish and rude. So now, not only was I already having a hard time seeing, our kids weren't able to see, and now, I have to stare at your child's rear end in my face. Even more fun when the child has a full diaper.