Teaching a group of children becomes less fun the older and less english-speaking the children are. For example, a group of Catalan secondary school students will make fun of you, and you will not know what they are saying. It also doesn't help if you're not much older than them, or support the wrong football team.

Lesson learned.

It's a metaphor of human bloody existence, a dragon. And if that wasn't bad enough, it's also a bloody great hot flying thing.