The act of having your children go trick-or-treating, and periodically returning home to get rid of the "crap candy" they don't want. Then, using that candy to hand out to the trick or treaters that come to your house. Very similar to re-gifting.
"Who gives a 3 year old jawbreakers and popcorn balls for Halloween? WTF!! We ended up re-treating those, and eating all the Hershey's we had originally bought to give out.