Originally in the Arabic street language, it means "your mother's vagina" - but although it's nature as an insult, it serves the purpose of the Arabic "God-damnit!" and if not the Arabian one, well, it's the formal Israeli one. For although there is a "Dammit" in Hebrew (La-azazel! , mainly) - in the rough streets of Israel and non-Israeli-city-as-known-as-Tel-Aviv (ha ha) - Kus-emec/Amac/ssssss-emec/etc. is the formal and non-formal "God-fucking'-dammit!". Also may accompanied with "+Ars" (will be exampled below), and by the suffix "sh'cha" and "ima" (mother) instead of emec which means - your mama.