Trick-or-treating or guising is a customary practice for children on Halloween in many countries. Children in costumes travel from house to house in order to ask for treats such as candy (or, in some cultures, money) with the question "Trick or treat?". The "trick" is a (usually idle) threat to perform mischief on the homeowners or their property if no treat is given to them.
Is this something you do every year? Are you going this year? Going to take anyone?