Chaffing and teasing, irony and 'having a laugh' is indeed the norm here in UK. I suppose it's what is known elsewhere as 'the British sense of humour'. Socially speaking, I reckon it's a way of actually blurring or softening direct criticism or disapproval. My friend Ronda had a German male friend, and when he visited from Munich he was horribly 'direct' in his utterances. He'd tell her, if she asked him for an opinion, that her dress wasn't attractive, that her figure was a bit fat, that the new sofa was a horrible colour etc. If she winced, he'd be amazed and say, "But...you asked me!" The humour approach backfires with Africans. If you 'joke' and say, for example, "Good grief! This spicy food will blow my head off!" they'll look horrified and reply quite seriously, "No, it is not dangerous. Please do not be afraid. Your head will not blow up." I often tell my husband that in the dark all you see of him is a set of white teeth coming towards you. He'll say, "But you know that the rest of me is there too!" It is very hard to make him understand one is joking or teasing.