Picture a child standing at a lit doorway on Halloween night, holding out a bag and offering the grown-up two choices in three words: a sweet, or a joke played on you. Everything else grows out of that doorway. The three words are the call itself. Walking from door to door all evening, saying it again and again, is the whole activity that takes its name from the call.
可以想成萬聖節晚上，一個小孩站在亮著燈的門口，袋子伸出去，用三個字給大人兩個選擇：一顆糖，或者被捉弄一下。其他的東西都從這個門口長出來。那三個字，就是喊出來的那句話。一整晚沿街一家一家走、把它喊一遍又一遍，就是這個以那句話命名的活動。
From the word’s history
The name of the activity is simply the words the children say: a trick played on you, or a treat given to them.
活動的名字就是小孩喊的那句話：trick 是惡作劇，treat 是給的糖。來源直接寫明，這句話的意思是「不給糖就捉弄你」，活動便沿用了這句話當名字。