, me and a few million of my closest friends are going to dress up as SYN
One of us will knock, and the person inhabiting the house will take a handful of candy and approach the door. Then another one of us will knock, and the person will halt momentarily before going back to get more candy. Meanwhile, more of my friends will start knocking on the door. Eventually, the person will be carrying so much candy that they will fall over from the shear weight of it all.
See, we're going as a Denial of Service attack.