Seamus was a substitute teacher who taught our class in the last year of primary school. We kind of called him Seamus behind his back because he lived just down the road from us, and that's what the parents called him.
I remember we'd been doing some lessons about the dangers of smoking. It was the usual stuff - rancid, rotting lungs that had been damaged by years of smoke filling them. Do you remember those specimens? The little microscopic bits of lung that were blackened and corroded? Yuck.
But one morning Seamus took the anti-smoking campaign to an entirely new level - he strutted into the classroom and produced a packet of cigarettes. Making quite a display of the next part, he took a cigarette out of the pack and lit it up. The constant background noise of the classroom died away as everybody realised the teacher was smoking in the class!