A spelled-out version of how some English speakers actually say 'your' or 'you' when they are relaxed and speaking fast. Nobody decided it; a writer heard 'get yer coat' instead of 'get your coat' and wrote down the sound. You find it in novels, comics, song lyrics, film subtitles and social media, wherever a writer wants you to hear a particular voice — often working-class British, northern English, Irish or Cockney, sometimes pirate-talk or a rough character in a story. It covers two different words. Most often it is 'your': 'yer man', 'mind yer head', 'shut yer mouth'. Sometimes it is 'you': 'I'll see yer later', 'what are yer doing?' You read it off the page and turn it back into the ordinary word. This is 'eye dialect' — writing that shows a way of speaking, not a separate word with its own meaning. It carries a strong flavour: informal, warm, sometimes rough, sometimes affectionate, and in the wrong place it can look as though the writer is making fun of how someone talks. In Irish English 'yer man' and 'yer one' have hardened into set phrases meaning roughly 'that fellow' and 'that woman' — the person we both know about but are not naming.