These are wonderful little things called Boo Grams.
A Boo-Gram is a mysterious note, left on neighbor's doors in the middle of the day. The note is usually a poem of sorts, and a large Boo decoration for their front door. The decoration serves as a means of communicating to other neighbors that this house has already been "hit". By Halloween, it is not uncommon to see Boo-Grams lining up and down the street on all the doors in some neighborhoods!
Accompanying the Boo-Gram is a collection of goodies, determined by the giver. The goodies may vary from small Halloween treats, to kid's toys. The magic of these Boo-Grams is the reciprocation of this gift, as it is expected that when you are "Boo'd", you must "Boo" 2 other neighbors as well.
Click this link BOO GRAM PRINTABLES to print off your boo grams for next year. What a neat idea for surprising your neighbors during Halloween. I loved doing this and will continue to do it every year. FUN FUN FUN!