What was the worst dirty trick ever played on you?

We did not pull pranks in our family. It seemed hurtful. Someone always ends up being the victim.
But one time, when my brother and I were about 8 and 9 we pulled a light prank on our Mom. It was shortly after Halloween. My brother secretly bit off the white tips from a few candy corn and kept them in his mouth. Then he and I pretended to be roughhousing in the back yard while my mother sat and watched. Suddenly, he made noise like he was hit in the mouth and began spitting out the white, saliva soaked tips. Some had traces of red-orange on the edges. They looked exactly like teeth.
My poor mother was horrified. And we felt terrible.

There’s a good chance that was the last prank we pulled.

The worst prank that I know of was pulled by some friends on someone else. A co-worker of theirs loved fish. So they filled the floor of his office with water cups each filled with water and a little fish. But the prank backfired. They did it after he left on Friday. The cups leaked, the water soaked his office carpet and the fish all died. The smell by Monday was quite horrible and not at all what the pranksters had intended.

In college one guy got pranked by his ex-roommate and friends. e came back from class and saw that the dorm room number and name tag were stuck on his door upside down.
When he opened the door he found that everything in is room was upside down: bed, desk, stereo, everything.
ha ha
I helped him turn it all back. We’ve been friends ever since. 40+ years.

I had a good friend who was the Academic Dept.Assistant at the Voc High School. She was as or ornerier than cat poop. An example: She handed out folders during meetings held by our sanctimonious POS dept. head- ( the one who wrote you up if you agknowledged a holiday for fear it would be offensive to some student? Yeppers, that was the same dragon.) So I get my folder and open it to find a plastic wiggly cockroach on the papers. Absolutely hating them, I gasped, jumping up out of the desk dropping and scattering my folder! Haghead stopped talking to pointedly look at me and asking if I were alright. I acted like I was having a coughing spell and pointed towards the door to go to the water fountain as I left.
A couple weeks later, my friend had an ill relative and was feeling low and tired. I happened to have walked over to get my mail and any write-ups bitchwad had created for our group. It was waaay too quiet in the usually busy and lighthearted atmosphere of the room. My friend’s desk faced a giant picture window out onto the hallway and the beautiful vista of the girl’s restroom! Yea! Her desk and counter was what greeted you when walking in the office.
I stood there reading the papers and talking. Nan was so sad. Sooo I put my mail back into my space and commented on the quiet, was there anything I could do to help cheer her up. She just shook her head and said something gracious- Where upon I said something to the effect of; The shit we had to do around here to cheer some ‘bitches’ up!
She and another teacher were startled, and kind of jumped and said something like.. I don’t remember, probably not to get in trouble again…as I walked out of the office and went to the left. The hallway was deserted with classes going on. I used my ‘teacher-voice’ and said; “Nan, this is for you…” Where upon I did my best Nadia Comãneci Olympic cartwheel in front of the vista window. Except that halfway through it, thinking I heard a kid coming down the hallway, I kinda/ sorta veered off course a little and crashed into the scenic window. The view of the Olympic cartwheel must’ve been spectacular ending up with my bluejeaned butt and legs, plastered up against the window as I skritched and slid down the glass into the heap of person that was me. All I said was: “medic…”
There was no kid in the hall, but by that time there was no way to have aborted the mission.
My friend Nan shrieked and fell out of her chair screaming with laughter, ending up on her knees in the “I’m looking for my contact” position. Another teacher slammed into the mailboxes and was holding them up from falling off the shelftop stand, while crying. And a younger new teacher had approached Nan’s desk to ask for something, just in time to catch the show. I don’t know. She loudly let out an ” OMG, are you OK???” Words you never say when you are ‘doing stupid’!!! “Oh shit, cheeze it!”, I thought, and quickly rolled across and into the girl’s restroom as Godzilla came out of her office. I still have no idea what they said to her about it all, to this day. But about two seconds later, Nan jumped over me-still on the floor, to make it to a stall just in time before she had an ‘accident’. She was still doing the calm-down whining a person does after laughing too hard. I just moaned and said- “Damn it all to hell, you’re going to kill me one of these days.” And we both laughed hysterically for another five minutes. Then the bell rang and I had to 4–40-it back to my building and classroom. I was late. I kept vearing to the side while trying to get there.
Probably my most colorfully painful, yet hardly my last prank.