Students will be checked in the morning for badges before entering the school gate.
[College students] go to school in the morning, singing songs in line like kindergarten children. At the university’s main gate, a student representative with an armband inspects the platoon coming to school. What to look for is whether the pants line is neatly cut, whether the head is properly cut, and whether a badge is worn by Kim Il Sung. If you receive an indication here, you will have to go home instead of entering the premises. (Chan Ki-hong, “North Korea: Ordinary People,”)
There seems to be unannounced inspection of passers-by.
When he changed his clothes and forgot his badge, he jumped out and was stopped by a teenage boy with an armband indicating that he was part of a social order squad. They were vigilante members of the Socialist Youth League, who inspected the public to make sure they were wearing their badges. The first offender must take a special thought lecture and penalize personal records. However, at that time, Mrs. Son realized that he had forgotten his badge at home, and the boy gave him a warning and released him. (Barbara Demick, Nothing to Envy:Ordinary Lives in North Korea)
It is not clear what will happen if the personal record is punishable, but it will probably be disadvantaged in future schooling and employment. It seems that it is not a serious crime because he gives up only by warning.
The following testimony from a defector shows that even if you forget to wear a badge, you will only need to say a few words.
My mother was stopped by five vigilantes in red armbands on a street in the city center. […] The nasty thing is that they often target the morning rush hour. Many people rush out of their homes and forget to wear their great leader pin badges. This is a small circular badge, which in North Korea is supposed to be worn by all adults around the heart. The vigilante will stop anyone who finds such a trivial problem. The trouble is, it is hard to say that the person who was stopped was “inadvertently forgotten.” You can be told what it is to forget the great leader. (Lee Hyun-so, David John “The Girl with Seven Names”)