i'd like to hear the teacher's version of events before passing judgement instead of a 3rd hand account from the GF to OP's 10 year old son to all of us... i'm sure nothing ever got messed up in translation like that ¯\_(ツ)_/¯
and if true, reading between the lines i'm guessing the teacher is a little disgruntled and burned out. probably in no small part due to OP's constant class clown antics. or the general failing of the education system. not saying it's a justified comment, the teacher should not be lashing out this way. there's good and bad ways of handling bad behavior, and that's easily a bad way. a good way would be to give him consequences that are directly related to the problem. she might not have time to do 1-1 behavioral training with your kid, the school probably doesn't have resources for that.
the teacher might be overworked, overtired and underpaid. OP isn't interested in correcting her son's disruptive behavior because he makes honor roll (like that justifies it) and maybe the teacher had a moment of weakness. so lots of bad parenting and bad choices all around.
i just don't like how quick people are willing to crucify a teacher over something we don't even have both sides to and is a more nuanced situation than OP's biased post suggests.