Best practical joke you've pulled at work

The shipping ‘bags’ that are basically just plastic air bubbles..... I always love taping them onto someone’s tires and watching them freak out when they leave and hear ‘POP POP POP’

Around the 1990 I made a fake virus, just a little graphic program that I put in a co-worker's autoexec.bat file. I found out later that he had already been a victim of a real virus, so when he saw this, he completely fell for it. I was able to catch him turning on his computer, and I saw him silently staring at his screen, just steaming. After a few minutes I tried to explain that it was a joke, but it took several minutes for him to believe me. It worked better than expected!

Hiding a coworkers desk top icons and putting the blue screen of death as their background

Fake lottery ticket showing a win for half a million. Co-worker ran out to get in his car & drive to Austin without saying a word to anyone.

Had to call his cell and break the news

Worked at a hospital where collecting urine samples was routine. A male nurse put some apple juice in a urine sample cup and secretly placed it at the corner of the nurses station. He left for a few minutes and returned when several female nurses were at the station. He said “God I am dying of thirst!” Walked over to the urine sample cup with the apple juice and drank it down in front of the female nurses.
A few of the nurses started gagging uncontrollably until the male nurse started laughing his arse off and told them the truth about the apple juice.

While maybe not the best....when i was in high school i worked at a grocery store... we used to lock new people in the dairy cooler in the back and say it was jammed and it would take a few minutes to get them out... we then would stack a bunch of milk crates in front of the door and put a gallon or two of milk in the top one (there was a an opening on side of the stairs to get to the top of the cooler)... once we were done we would tell the person to help push from the inside. Person would push with all their might and then GA-DOOOOSH....milk everywhere

i worked for IT on campus in the early 2000s when the internet was just starting to really be mainstream. a bunch of 20 year old guys just screwing with each other every day.

main thing was that if you walked away from a computer in the office unlocked, when you got back your desktop would be goat.cx, or lemonparty.

eventually i got a promotion to be a server admin so i had control of everybody's accounts, including my coworkers' student accounts. friend logged into class and i had used group policy to put an inappropriate desktop on all their accounts and one dude logged into a presentation station and had a bunch of naked dudes pop up in front of his class.

his retaliation was taking my keys out of my desk when i stepped away and parked my car in BFE and then a week later in my boss' spot.

Messing with people's computers left unlocked while they were away was always fun. I'd connect to the unlocked computer via MS Netmeeting and allow myself access to control their laptop. The great part about Netmeeting was that it wasn't incredibly obvious that someone was remoting into their laptop. Once the person returned, I'd crank up the volume to their music and blast some music. It was pretty great if you were nearby and could hear the person's reaction and the music blasting.

Another things I'd do when someone left their laptop unlocked was to get on the person's messaging app and start chatting with a coworker. I'd usually ask the coworker in the chat if I could borrow a few dollars for something. Later, that coworker would come by with the $ and the coworker with the unlocked scream would be dumbfounded.

In college, while another student worker was away, we'd change the browser homepage on their computer to some page that would start looping an audio that said "HEY EVERYONE! I'M LOOKING AT GAY PORNO!!!"

A former boomer boss hated tattoos, and deeply resented the younger generation for embracing them. She even wrote a policy banning visible tattoos.

I was the #2 at the time and bought a pack of fake tattoos before we visited one of the more distant locations where there was about 20 employees. I made the rounds to each employee and convinced them to put on a fake tattoo before our group meeting. The tats were not obvious- just a star behind the ear, a neck tat peeking out slightly above a collar, a wrist tat, and so on. But a young lady my boss hated the most agreed to wear a leg sleeve that showed below a skirt.

I knew the agenda was going to be rough so I did this to soften up the employees. My boss knew the news was rough too, so she was reluctant to raise overwhelming policy violations that were visible in the meeting during the meeting, but I could tell she was fuming.

On the drive to the airport, she was dramatically unloading about the issue. I added fuel to the fire about how disrespectful that was to her policy. She immediately decided to address the issue with the middle managers in that location and started to call them to bitch about it and belittle the managers. As she dialed the phone number, I asked her to check the date before unloading on them. It was April 1st. She took it well and took a knee.