Sir, tell him! He's cussin' my mum!" says a bleating and tedious infant in the back row. Mothers this week have been called slags, muppets, tarts, turnips - and a budgerigar. I glower.
This is all the rage. The brute observation, then the pause, then "Joke!"
Less callous examples this week have included: "My desk's on fire! Joke!"
"I'm pregnant! Joke!" "Your mum's a prossie! Joke!" "You got a face like a pizza! Joke!" "Are you a poof, sir? Joke!"
It doesn't make the spirits dance. What has happened to schoolboy humour? That Kingdom of the Absurd born of boredom and bullying, with its patron saints Tommy Cooper, Peter Cook and the ineffable Molesworth. My past pupils could render me helpless with laughter.
My own grammar-school days were spent howling with mirth. What happened to those elegant time-wasters, camp ironists, inventive dossers and dreadful punners? We were so much more sophisticated than this lot. And probably more sadistic. Especially with my French teacher Emlyn "Chunk" Jones, a Pentecostal maniac from the Welsh valleys.
He bellowed and blasphemed and hit us with sticks when we couldn't conjugate. He put Rumble's head in a desk and banged it with the lid, which did nothing for his pluperfects. "It makes a bad impression on my mind!"
observed Rumble wittily. Chunk went haywire and caught his gown on a nail.
He looked like a billowing Dracula. There was a fabulous ripping sound. How we laughed. He didn't. He talked in tongues and hit us with a stick in all directions.
We took our revenge with devastating schoolboy wit. We took his lectern to pieces and stuck it back together with Airfix glue. Chunk charged on to the podium, leaned on the lectern and collapsed out of our sight. Only his sulphurous skull was visible.
"This is not a laughing matter!" he thundered at the laughing mob. It struck us as most satirical.
"Joke !" we should perhaps have yelled.
Classrooms are less funny these days, probably because they're less attritional. Or we've all been rendered witless by management culture with its targets and tests and tedium. I miss the larks and lunacy - they've kept me in teaching. I look up the philosopher king Molesworth for some sophisticated stuff. There is a cartoon of Fotherington Thomas.
"You kepe dollies at home and hav a face like a tomato!" observes Molesworth.
Oh dear. Well, it still makes me laugh. He doesn't even need to yell "Joke!"