Teachers often moan or complain about their work. Other people can get tired of this, as teachers get long holidays. Lines such as 'well you chose the career' are uttered. As a teacher, I think I understand why teachers complain so much.
It's not because teachers don't like their job, and it's not because they really hate the kids. It's because teaching is genuinely a very difficult job (that's why we need the holidays!), and complaining (or 'downloading' as I prefer to call it) is an important coping mechanism. Ranting is satisfying and helps release the stress. The best people for teachers to rant to are other teachers. It's about 10 times more helpful to moan about school to another teacher than to a non-teacher, simply because you know that another teacher faces similar difficulties.