http://jonathanjnorth.blogspot.com/2013/10/amazing-trick-or-treat-ideas.html
Again, this probably goes without saying, but:
Warning: Do not actually attempt any of these in real life. If you do, be aware that results may vary, from mildly scarring a small child for life, to receiving multiple lawsuits from angry parents.
Dog Biscuits - Open the door and ask the child if they've been a good little boy or girl. When they inevitably lie to your face and say yes, act thrilled. Exclaim, "Wonderful! You get a treat!" Pull a box of MilkBones off the table inside the door and drop one into their bag. Ruffle their hair, and rub both cheeks in your hands exclaiming "Whosa good boy! Whosa good girl!" adjusting the gender as necessary.
A Duck Wearing a Propeller Beanie - Open the door and let the duck waddle slowly outside to the child, propeller gently turning in the breeze. Leave the door open so that the child can hear you quietly weeping inside.
Coon-Skin Cap - Open the door and place the cap carefully on the child's head. Tell them, "I caught that there possum just this mornin'! He sher did put up a fight." Hold up a hand covered in ketchup that seems to be missing two fingers. When the child throws everything into the air and runs away screaming, lift the two hidden fingers back up and laugh evilly to yourself while you collect their candy.
Door Knob - Jerk open the door as hard as you can. Rip the knob out of your door, preferably splintering the wood around the whole knob, pulling the entire locking mechanism free. Yell, "Fetch, boy!" if it's a girl, "Fetch, girl!" if it's a boy, or "Fetch, thing!" if the child has no discernible gender; then throw it as far as you can. End the encounter by slamming the door and using a nail gun to violently nail the door shut from top to bottom.
Lemon Meringue Pie - Whip the door open as fast as you can, and >SPLAP< the entire pie in the child's face, knocking them off the porch into the shrubs. Slam the door and run out the back in order to escape the police.
Infant Baby - Walk slowly outside, completely disheveled, wearing old pajamas that have questionable green and yellow stains covering the front, with a tattered robe overtop that has fallen off one shoulder, holding a baby that is screaming at the top of it's lungs. Make sure you get a baby that has mastered the theatrical arts, so that when the infant sees the trick-or-treater, he, (Or she, you won't know until the first diaper change) will immediately stop crying, reach for the child calling, "MAMA! MAMA!" and leap into their arms. You then shriek, "THAT'S YOUR PROBLEM NOW, SUCKA!!!" and slam the door in their face, lock the deadbolt, close the curtains, and turn off all the lights, while you hide in the basement behind the water heater.
Balloons - Walk out, tears quietly streaming down your face, holding a handful of popped balloon shreds. Sadly say, "They're dead..." then sprinkle them into the child's bag of candy, turn around, and walk back into the house.
Macaroni & Salt -Walk outside with a box of your finest Barilla and a carton of your almost finest Morton, and pour all the macaroni and half the salt into the child's bag. Exclaim, "It's a do it yourself dinner tonight!" Then roll your eyes backwards, and start moaning and rambling incoherently, while turning in a counter-clockwise circle, pouring the remainder of the salt in a circle around you. Turn back to the child, and if they haven't run away in terror, smile and say, "There! That'll keep the Zompires away!"
Candy Corn - Give the child candy corn. Sit quietly while the child eggs your car, TP's your house, and tars and feathers your body. You deserve it for giving out candy corn.
Kool-Aid - Stand outside next to a very large potted plant. Wait until a child is within earshot, and loudly offer the plant some water while holding a comically over-sized watering can. Pretend the plant has accepted your offer, and then unscrew a bottle of Dasani out of an overhead light fixture, and stab it upside down into the dirt. Pretend to react to something the plant has said and hide the giant watering can behind your back and patronizingly explain to it that it is not allowed to have sugar. When the child steps up and says "Trick-Or-Treat," ask them if they would enjoy a fruity beverage. When they reply, pull out the watering can and sprinkle neon blue Kool-Aid over their head. Toss three ice cubes in their sack, and skip into the house, leaping into the air, clicking your heels together, and slamming the door behind you.
