"Trick-or-Treat!"

"Trick-or-Treat" is what kids say when they go trick-or-treating on Halloween (October 31st), which is traditionally going door-to-door in your neighborhood, dressed in a costume, asking for candy. Some communities hold trick-or-treating on a weekend night that is closest to Halloween. In the interest of safety, it is now common to see trick-or-treating offered by malls or in other shared, public spaces. Some churches or other organizations also hold a 'Trunk-or-Treat,' where kids go from car-to-car in a parking lot, collecting candy from people who have have their trunks open to show off their Halloween-decorated interiors.

Traditionally, 'trick-or-treat' meant 'Give me a treat or I'm going to play a trick on you." Tricks included such things as soaping windows and egging houses. Now it just means, "Look at me, all cute in my costume, and may I have some candy, please?"

Example:
-Trick-or-treat!
-Here you go! Please, take two!