Search Result for "trick or treat":
Wordnet 3.0

NOUN (1)

1. a request by children on Halloween; they pass from door to door asking for goodies and threatening to play tricks on those who refuse; 



WordNet (r) 3.0 (2006):

trick or treat
    n 1: a request by children on Halloween; they pass from door to
         door asking for goodies and threatening to play tricks on
         those who refuse