Schelm means: A rogue, villain, or scoundrel - used in both Scottish and South African English. In South Africa, where it entered through Afrikaans and Dutch influence, it remains in active use with a slight. The word is mostly archaic or historical; you will only encounter it in old texts, period drama, or school history rather than current teen conversation. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour.