What's the harmless funniest prank you played on someone?

In the early 1970's I worked in a carwash in Nanuet, NY.
It was brand new, and we were only in business a few months when they brought in some equipment to get us through the Winter; an "air curtain" a big heavy machine that kept the water from freezing inside.

To lift it into place, we also had a HD fork-lift.

Turns out the boss drove a VW "squareback" a little 2D station wagon.

When he wasn't looking, we used the forklift to pick up his car, and set it on the flat roof of the carwash.

At first he thought it was stolen.
Then, in mock surprise, I told him: "There it is!" and pointed to the roof.

He didn't know how to work the forklift, but we let him fiddle with it a little before we set his car back down on the pavement.

I am guilty nobody got hurt or anything. I took a label off soft drink bottle. I was drinking Dr.Pepper. Well my grandmother liked coke cola he did not liked Dr.Pepper. I gave her bottle it is coke would you liked a sip. And well she was liked yeah sure. Well she sip the next thing see is her making funny face. I could not help it. It was April fool day and that was why I did that.But to say the least it wasn't real bad.

One of the skydiving instructors where I worked had left his parachute laying on the floor unpacked. When he wasn't looking, I took all the little pieces of paper that got punched out while I was binding instruction manuals and put them into his parachute. The next jump he did, his parachute opened, and confetti fell all around him. He landed and was like, what the h3ll!?!!?

OMG if I started telling all the pranks I have played on people I will for sure die and old maid.

In 6th grade, during recess, I persuaded some of my classmates to help me steal one of the faculty member's cars. It was a VW beetle.
She had left the door unlocked, and back then there weren't steering wheel locks or other such anti-theft devices.
We pushed it from the front of the school building to the back of the building.
Then the bell rang, so we went back inside.
Some time later the teacher showed up in our classroom, in tears: "My car's gone!"
Our teacher went outside, found it where we'd left it, and rolled it back down the hill to where it was originally parked.

Good times.

Over a decade later I was in Germany, and some friends and I were walking to a bar when we saw a tiny car parked by the side of the road. Didn't take much discussion, we just picked the car up, and turned it around and set it back down, facing the wrong way.

More good times.

There's a tiny car called the "Smart".
In Venice, it's a popular hobby to toss them into the canals.

Don't give persons food or drink they don't like.
You could killed them or start an allergy or intolerance. They may be allergic to it.

Crime should not be a hobby.

My April fools japes were putting paper in a cardboard or plastic container on a door top so that when someone came into your room the paper confetti fell on them

As a teenager, I helped put a large sign on someone's front lawn

Did you see the blind man walk into a bar, chair, table

Linguistics joke: What happen when an Englishman, Irishman, Italian, and American walked into a bar?

'Oh I say. Ohh, by gorra. Eee... Where can I complain?'

when I was around 13 years of age .I thought it would be funny to spray my sister through her bedroom window with the garden hose while she slept ..so I got a friend of mine' to put me on his shoulders and carry me over to her window! because it was quite high up ,but what I did not realize was well we were getting ready.. my sister woke up and was watching us through the window! so when we made our way to her window.. and right when I was about to slide the window open she threw the window open and grabbed me by the hair on my head my friend bolted leaving me literally hanging there I still have a bald spot to this day lol

It was in the first year of marriage ex kept going on about this hot Currie he had in Fiji. I got tired of listening to it. I cooked curried sausages and chucked in noodles from one of the Asian countries. Wow it was burning hot. Ex comes home from work I dish it up. He starts to eat it and tears roll down his face. I ask what's wrong he replies it's to hot I can't eat it. I looking dumbfounded but you said you like hot Currie. Lol never went on about it again.
Lol one of many times I got pay backs. Revenge did taste sweet.

n1,
To thank her for the bald spot; get into her bathroom, and loosen some of the light bulbs, so when she turns the light on, it's kind of dark in there.
Then with toilet lid & seat in the upright position, cover the toilet bowl with Saran Wrap (the kind of clear food wrap that in the UK is known as "cling film".
When she goes in there to pee, it'll be too dark for her to see the plastic film, the pee goes all over the place, except in the bowl.

:) The guys decided to xerox our butts / balls from an old model copier in our frat house. We went to Kinkos to print more copies on color paper that evening. The next day, we all planned to raid the printers in our premises by sneaking in & replacing the papers already in the tray with our one-sided printed copies. Lets just say that one of my class, we took a quiz & printed out our a.ss-ay.

I was using the port a potty and my phone fell down the hole. I decided to call it when somebody went in there. I had a witch cackling for my ring tone. I called my phone from my friend's phone. The man came running out buttoning his pants with a bewildered look on his face. A lady went in and I called my phone again. She ran out like she had seen a ghost. The third time the phone died. At least I got a few laughs before I lost my phone completely. Bittersweet.

I think one of my funniest practical jokes was not really a planned one just one of those "devil made me say it" remarks.

My friend who also was a foster Mom and day/night care operator had and emergency and brought all her "brood" over before a hospital run.

My husband after a long and tiring deployment came home and they were all spread out over the living room floor sleeping soundly.

Now keep in mind he knows I am a soft touch for kids in crisis and was not unusual for us to have an extra under variance even on our care license.

I see him counting noses a couple times, he goes down the hallway and checks on ours, and you can just see the wheels turning as he returns and is wringing his hands counting off the little bundles.

He says rather resigned "How many are staying?"

To which I promptly replied "ALL of them." and scurried off to the kitchen suffocating the giggles.

I guess he figured he should get sleep while it was an option because gear and all he collapsed in his chair and promptly went to sleep.

Worked in a fire station for several years and, with 24hrs per shift, we always played the usual pranks on each other.....send the new guy after a left handed spanner wrench, or tell him to go get some water hardener from the chief....flour each others beds or if we filled in at one of the older stations, we would stretch saran wrap over the toilet underneath the seat. The bathroom lighting was bad at those and you couldnt see that tightly stretched wrap until you actually peed. You could also position the water supply line out the back of the tank lid so the water wld run all over the floor when the toilet was flushed
There used to be a Valtrex genital herpes commercial with an 800 number to call for info and someone wld call and give a married guys name and address for an info pack to be sent to in hopes his wife got the mail.
Yea yea, juvenile stuff but it was good times.

I used to work in a factory, with a co-worker that was a practical joker, & married.
His wife called for him one day, though I answered the phone. The call came shortly after he'd tried one on me.
I didn't want to do anything elaborate.
So I just said to her:
"Hang on, I'll go get him; is this his wife, or his girl friend?"

Took care of that! (I gather he had the dog house carpeted)

PS
I'd like to congratulate myself on reaching the century mark on my post counter here @mingle2.

Good one!

They all got mooned and then some!

Ha ha ha ha now there is an original prank not meant to be in the first place!!!

It just over loaded him!!