Walk back and say something?

When you sneeze, your waist flashes every inch of your body. The literal meaning of this idiom is very simple and easy to understand. It is a normal thing to sneeze, but it is just an inch of effort to flash your waist. (Cunjin is a Northeastern dialect, which means catching up.) In real life, this catchphrase is mainly used to describe things that should not have happened, but happened unexpectedly. Things that are not related to each other, but they are not related at first. Ran into it by chance.