Nothing makes me dread walking into a room more than when the teacher standing outside looks like he has just lost a fight with a pit bull and his greeting is, "Be careful of his teeth, he bites".
The next 60 minutes are unpleasant. The pupil is in full double-restraint position. All of the procedures have been followed since the initial incident. All de-escalation techniques and warnings have been given, there is member of the senior management team on hand, a first aider is present and there are staff out of sight, waiting to take over if needed. We are all aware why this is necessary, because of the state of the room, our staff and the pupil's parents. We are protecting this pupil from himself.
Occasionally, there is a flash of white as he attempts to bite my colleague and I on the face. When that fails, he contents himself with spitting on us and calling into question our parentage, critiquing our body shapes and giving contradictory descriptions of our perceived sexual activities.
This is in a mainstream school. This is not a secure unit with locks and rubber rooms. This is not Hannibal Lecter. This is a pupil who is so angry, for whatever reason, that he felt destroying a room, attacking his parents and our staff and finally barricading the door would solve all his issues.
The one thing I held on to, other than his thrashing arms and his head, was that this is legally a child. Big, muscly, hairy and scary, but still a child, with a child's ideas and a child's reasoning skills. As I talk to him and try to calm him down, I repeat this simple truth to myself. He may be trying to bite me, he may be leaving saliva stains on my trousers, but I keep talking quietly and kindly.
After a while, you can almost sense the desperation as the pupil realises what is happening and slowly calms down. You have to hang on until you are sure of the outcome, but eventually the plan is to let go and find a way out of the dead-end towards which the pupil is heading. The end is in sight.
In the immediate aftermath, a member of staff trained in counselling moves in to support the pupil and we trudge away to the staffroom to drown our sorrows in coffee. We are tired and have a lot to talk about, but we sort ourselves out because we have to consider the next 30 pupils.
Now I remember that incident every time I think a group is bad. I think, "I have been to hell - this lot are pussycats by comparison". I wished the pupil well and shook his hand when he left the school six months later, but he will always stay with me as a benchmark of how bad things can get.
Luckily, no subsequent pupil has yet come close to that.
To tell us what terrifies you or to share the unscripted events that have happened in your classroom, email firstname.lastname@example.org.