Not a particularly clever prank, but I got a laugh today telling my students that we were having a surprise midterm. 
Here’s one of the other forums I frequent.
Oh yes, and I noticed the forum here was down earlier. I went back to the main page, I saw why. More Cat Pictures indeed!
This is an ideal office prank - we used this on one of the lads in the open plan part of the office.
(He also lives on a farm so this was doubly appropriate!)
There’s a fantastic website for a tweeny magazine called “I Love Horses” - I **promise **this is Safe For Work (it’s past 12pm here, so this isn’t itself a prank):
www.deagostini.com.au/ilovehorses
When you load the site a midi file plays automatically with a truly cringe-inducing song: “I love horses… best of all the animals! I love horses… they are my friends!”
Prank as follows:
- Open up main web browser
- Change home page to “www.deagostini.com.au/ilovehorses/”
- Set PC volume to max
- Close browser
Then just wait for the victim to load up IE or Firefox etc - our office now routinely has this song blaring out as yet another victim gets caught. 
Thank you:D:D:D:D:D:D:D:D:D:D
I think I might try something like this!!
More typically, methylene blue turns the urine green because of the presence of yellow pigments in normal urine.
It will turn it blue if the urine is dilute or for some other reason does not contain a very high concentration of bilirubin.
Excellent username/post combo, Chief Pedant.
Last night I switched the M and N keys on my boss’s keyboard (she’s a hunt and peck typer). This morning I heard her frantically calling for her assistant saying something was wrong with her keyboard. She thought she had spilled food in it or something. The assistant was in on it and finally had to fess up that it was me.
I apologize.
I am in therapy* for this sort of problem.
*My therapy consists of my children berating me for pedantry.
I switched it up and intend to post this in my computer lab classes today:
Voice Commands have been activated on the computers in this lab!
You may now use verbal command and options instead of pushing buttons. For example:
“Open, Adobe Illustrator, Pattern File”.
Please enunciate clearly.
If command is not accepted, say “Reset” and try again after 10 seconds.
I just got 3 outta 5, and suddenly all the ladies had to pee. I’ll sneak in later!
Thank you!!!:p:p:p:p:p:p:p
My coworker got our manager good today. My coworker had to push out her retirement last year due to the economy. This morning she sent the following email to our manager
Subject: Announcement - please read
Importance: High
Jeff,
Due to some recent developments, I have been afforded the opportunity to retire earlier than expected. I am excited that I am able to pull this in even though I know it will bring some difficulty to you and the group. I am going to make April 15th my last day. Please take this as my official two week notice. We can talk as soon as you get a chance. I am both happy and sad (mostly happy) by announcing my retirement early, but am now ready to enjoy what life has in store for me.
Coworker
Everyone in on it knew the moment he saw the email as he said “Oh Shit!” and got up and ran to my coworkers cube. Most of us are still laughing.
I do this with one of the wireless touchpad apps for the iPhone/Touch and mess with people trying to play Bejeweled or whatever. With the apps working via WiFi there’s greater range and if you’re near enough for them to see you it just looks like you’re using your iDevice as normal.
I sent my wife to work with the Canon version of this voice-activated printer gag. She just sent me an email saying it’s working. One co-worker tried it and said, “it doesn’t work” then left, clueless. Everybody else just said they hope the other copiers in the office don’t get the new feature.
Now, when people tell the printer to print or whatever, she’s sending an “Gotcha” Word document to the printer.
She works with idiots.
The best prank I ever heard of was the one where a roommate went away for a few weeks, so all the others in the house removed the door to his room and walled it over, painting and sanding and adding baseboards to make everything look original.
Then when the roomie came back, everyone acted as if he was a stranger. “You live in Room 4? There’s no Room 4 here. Who are you?”
This is even better if you do it with a laptop.
My friend once did something similar for real with 5000 dollars worth of mainfrome memory modules, which were service parts for a call. Went out to the car, put the box of modules on the roof, got in, drove to the site, got out, couldn’t find the modules in the trunk, went back, and there they were… all over the road, getting flattened by passing traffic. 
Check out the wbsite for John[del]s[/del] Hopkins University. 
I love it.
On April 1st some years back, we organized a resignation letter campaign. Everybody in the office who reported, directly or indirectly, to a particular director (about two dozen people) submitted resignation letters to him the same day.
He has allegedly still got them all tucked away somewhere, just in case he ever needs them. 