Funny story:

Around 5.5 years ago when my son was 8 and my daughter was a baby, my son had been watching some kids show and the kids were pulling pranks on each other. He declared "dad, I want to pull a prank on you". To which I responded "no you don't". And he insisted "I really do". So I said "ok, but be aware that when you prank someone they typically prank you back but harder. Then you feel the need to prank them back but even harder than they prank you and this is how prank wars begin. So, you can prank me and start a prank war but I will end it". A bit puzzled he replied "End it. What do you mean". So I continued "well the prank war will typically end when one person or both people can't stand the uncertainty of not knowing when and how they will be pranked again, so I will just tell you now what my final prank will be that will cause you to surrender. One day when you are sleeping, I am going to sneak into your room with one of your sister's poop filled diapers and place it on your pillow. When you roll over your face is going to roll onto a poop diaper. So, you have two options don't start a prank war that will inevitably end up in this situation or never sleep again. Do you still want to prank me?" He replied with a resounding "no. but can you help me prank mommy". I sighed and said "ok but she is going to get you back. I am just warning you. She makes your food."

So one day when my wife had a smoothie from the local juice place, when she wasn't looking my son and I got a little piece of some chewed gum and shoved it down the straw. When my wife tried to drink her smoothie nothing would come out. Suck harder, nothing. My son is laughing hysterically and my wife looks into the straw and sees the gum and says "what the hell" and looks displeased. My son realizes he is the only one laughing.

A few days pass and I see my wife in the kitchen. She opens a can of gingerale, pours it in a small opaque kids travel mug and then dumps about 4 tablespoons of salt in it and stirs it up. She calls my son to the kitchen and says "here I have a treat for you, some gingerale". The kids don't get soda very often so he can't resist and takes a giant gulp and then runs over to kitchen sink and spits it out. He says "what's wrong with this" and I just said "I told you not to prank the person who makes your food."

Prank war over. He never brought up pranks again.

Here's one I did that a friend is still angry about. A few years ago, when the price of oil went negative, I told him I had a good deal on a used fuel oil truck. I pretended to offer him to go into partnership with me on the truck. I don't remember the numbers. I said I would park it in the woods behind my house and sell the oil when the price spiked. That of course would be really hard to do, for so many reasons, but he didn't know that. He refused because he didn't have any disposable income. Then I made up this whole scenario when the price started to climb back, bragging about my profits. Kind of dumb joke, but it worked on him.