There is one teacher at DD's school that has nicknamed her 'chav'. Am I upset by it? Nope.
This teacher and my DD get along famously, he is the reason my DD stopped being anxious about attending school - because she knew there was the possibility of him joking with her.
He is a wonderful teacher, and knows just how to ease my DD's anxieties (she has LD's).
DD isn't bothered by it, in fact she positively revels in her nickname, and on non-uniform day, she asked me to help her dress head-to-toe in Burberry. The teacher nearly died of laughter!
They have a wonderful working relationship, and it has helped to bring my DD out of herself, as at Primary school, she barely spoke to anyone.
I wouldn't give two craps if the teacher had a hot drink. And the occasional slip of the tongue to say what this teacher did? Meh. By 15, they will be using worse, and hearing worse in the playground.
And anyway, if he was swinging on his chair at 15yo, then he WAS being a bit of a twat - my 9yo with SN's knows not to do it, so why doesn't a 15yo?!