The answer is “very carefully.” Context determines the meaning of many Aussie slang terms. Dacks is an Australian slang term for trousers, which could mean long slacks, shorts, or underwear, depending on the context in which the word is used. If someone is wearing trousers on a cold day, then dacks means long trousers; if it’s hot out and they are wearing shorts, dacks means short pants. But if a female is wearing a dress or a skirt, then dacks refers to her underwear.