In my textbook, it says "any attempt to reduce unemployment below its natural level is therefore foolhardy and irresponsible. In the short run it leads to accelerating inflation, while in the long run it will eventually create a hyperinflation, which, in the resulting breakdown of economic activity, is likely to increase the natural level of unemployment".
Should I interpret 'hyperinflation' to mean high levels of inflation? If so, how would that look like on a long-run Phillips curve diagram? Since the Phillips curve is downward sloping to the right, I don't see how you can have high inflation and high unemployment both simultaneously, unless it only happens in an extreme scenario (hyperinflation).