Isn't it old English usage or poetic usage at the end of a sentence?

This usage is a common usage in English and can be seen in many stage plays, such as some Shakespeare's plays. It only appears in British English, and American English has a short history. But "bu" appears at the end of the sentence, and it also exists now, but it is more common in spoken English. Used to tease people, often used by young people. For example, you are such a good person. Everyone likes you ... no, ha ha ha.