Of course, none of us would ever really do this, but it could be fun to think about it.
So, what treats would you like to give out if you didn’t mind pissing off the trick or treaters, their parents, and/or local law enforcement?
Those little sample 4 packs of cigarettes.
Airline bottles of booze.
Jack Chick tracts.
Cherry bombs.
Homemade caramel apples, only you use onions instead of apples.
Florets of broccoli.
Apple and a pack of razor blades.
Tell them they have to assemble it themselves.
Insulin pens.
Leftover eggs from last Easter.
Chick Publications has great ideas on passing out their tracts to kiddies on Halloween.
fire crackers and matches?
broken ant farms
porn movies
ink leaking pens
those pens with the dirty pictures inside
colored eggs but really raw inside
a small bag of grease masked as water balloon
popcorn balls laced with chili powder or something hot related
a cell phone loaded with dial a whore or whatever it is that you call and get talked dirty to
chewing tobacco wrapped like candy
toy guns, if you can find some
homemade McDonalds gift certificates
homemade candy straws only they are filled with sugar laced with powdered laxative
Individual Tic Tacs
Old Road Maps
Staplers and other office supplies (Thanks, Grumpy Old Men)
Little bottles of Shampoo, Conditioner, and Body Lotion taken from Hotel Rooms. And those little individually-wrapped soaps, too.
Old America Online signup CDs
My mom used to fill lunch bags full of treats for kids she knew and ones with really good costumes. If parents were walking around with the kids, they were offered Pepsi or beer. Our house was very popular.
lots of little brown bags - instructions not open until home.
(why yes, we do have a dog, thanks for helping).
So…you’re proposing giving outraged and disappointed kids ammunition???
Iocane powder in sugar packets.
Hey, the parents had ample opportunity to build up their kid’s immunity!
My dad (born in 1934) claims that when he was a boy, certain people in his neighborhood would hold out a pan filled with pennies and tell the “Halloweeners” to “take as many as you want!” Such a “generous” homeowner would, however, have just taken the coin-filled cookware off the top of a burning stove, and would commence laughing evilly as the greedy children hastily withdrew their now all-too-literally “hot little hands” from the pan.
Of course, that was when even a single penny was worth something – the “trick” wouldn’t likely be as successful today, and would certainly result in a huge lawsuit if some unsuspecting kid “bit”.
Rocks.
Or rather, popcorn balls, packs of gum, chocolate bars, and a rock for the one kid who had trouble with the scissors.
Genital-shaped chocolates.
Or along those lines, packages of edible panties.
I want to submit Kinder Eggs. All of Europe loves them but apparently our U.S. authorities think American kids are too stupid to know not to eat the toy. Customs and border patrol will actually confiscate them if they find them in your luggage.
My parents used to give liquor to the parents they knew who were with their kids. Trick-or-shots!
ETA: I’ve been threatening to give Chick Tracts to those kids who come by without a costume. You know the age.
Handful of aspirin tablets
A cherry tomato
Baggie full of mashed potatoes
Cardboard coaster from a local bar or strip club
A toasted marshmallow
Half a grilled cheese sandwich with a bite taken out of it
A sheet rock screw
A Milkbone
It’s probably a good thing I turn the lights out on Halloween… 
I went through the supermarket line on Halloween night with a bag of apples and a package of razor blades.
(Even though I had nothing else, the young checker didn’t notice. I should’ve just given up, but I had to point it out to her. Her delighted scream was so piercing that it sounded a lot like a real one.)
Felix Unger used to recommend broccoli-flavored bubble gum packaged with opera star trading cards. Not very evil, but sure to disappoint.
For Felix, that was evil.
One year, I didn’t any candy to give out so I gave out rocks. Not small rocks that you could swallow…probably egg-sized rocks.
I thought it was hilarious.
Anthrax. If your going to be evil, you should go all the way.