"yersel" means: Geordie dialect pronunciation and spelling of yourself, typical of the Tyneside accent of northeast England. Used in natural speech exactly.... This is technical or formal vocabulary, more likely to appear in school work, news or a particular profession than in peer chat. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your child uses the term, it is usually a sign of curiosity about a subject area. A short follow-up question about where they came across it is usually all that is needed.