This is from my time in the UK in 1990
German Erasmus Student: Bloody hell!
British colleague: Hey!
Me: What?
British colleague: He's not supposed to say that!
Me: But you say it all the time!
British colleague: But he's a bloody foreigner! He's supposed to speak proper English.
Said British colleague now has teenage kids of his own, I suppose he has learned the hard way, that kids don't do what you say, they do what you do.