| a children's Halloween custom, in which they call on neighbors, using this phrase, and threaten to play a trick if a treat is not given. |

| trick or treat interj. Used as a greeting by children when trick-or-treating. |
trick or treat
A greeting by children asking for treats on Halloween and threatening to play a trick on those who refuse to give them. For example, The children went from house to house, shouting "Trick or treat!" [c. 1940]