Other forms: scrammed
Scram means leave at once. Barked at somebody you want gone.
It is informal, slightly dated and almost always an instruction rather than a description, so shouting at children to scram is the classic use. It has a cheerful quality that stops it being genuinely aggressive. Clear off and get lost do the same job in British English. There is an entirely unrelated technical sense in nuclear engineering, where a scram is an emergency shutdown of a reactor.
1verbscramTo leave quickly, used as an order.
“Go on, scram, before somebody sees you.”
Also accepted in games: clear off, get lost
Scram began with claws. The word is a variant of dialectal scramb, to rake together with the hands or scratch with the nails, related to Dutch schrammen, to graze or scratch.
Probably either:
Etymology from Wiktionary, CC BY-SA