As a teacher you really do need to think about what you say before the words leave your mouth. (Although I do realise this can be easier said than done).
Today, I was screamed at on the 'phone to pick up one of my kids as he was quite literally bouncing round the classroom. When I arrived he stopped immediatley and smiled sweetly.
She [the supply teacher] had said 'You can be as silly as you like as long as you don't touch the teacher's desk'. He took this as his cue to do a Skippy impression across all the other desks (spurred on by the Jungle programme).
'I didn't break the rules, miss, so you can't tell me off'.