Accepted informality and slang. Hmmm, very good question. Interesting question. I don't accept skibidi or riz just as an example. Those are not even words. I do not accept "ain't". Informally, conversational words, personal words. There may be words/phrases that other countries misunderstand. But then they have a Some that I may do, in return. I'm not a master of my own language, especially when I can't speak it. These are my own opinions