Another pet peeve - when people mistake the names of events, attractions, and parks. By a longshot.
For example, when people refer to Magic Kingdom as Disney World or Disneyland.
Or, as some of you know, at the end of the school year we are going to Gradventure as a celebration. However, each and every teacher or administrator refers to it as: Grand adventure, Grad Bash, Graduation Adventure, or something along those lines.
There are posters all around the school with GRADVENTURE clearly spelled out for you. You're in charge of the trip, and yet you can't get the name down?
I know it seems trivial, but it gets on my nerves.