Pranks that take an age to set up usually aren’t worth it. So, while it’s possible to grow grass in someone’s keyboard or go crazy with the toolbar buttons in Office 97, that’s an awful lot of effort for relatively little reward.
The example on how to pull-off an office humor and pranks is to unplug your co-workers' mouse or keyboard from their CPU and plug-in your own to have complete control over the computer without him/her ever knowing. So now, whenever they move the mouse or type something. So do you..but of course it’s your input that controls what happens on-screen.
Add a wireless adaptor
Wireless mice are full of pranks potential. Install a wireless mouse adaptor on your target victim’s computer when nobody’s looking. Leaving their existing mouse connected. Windows can and would accept input from both devices, so wait until your victim’s doing something and then send their mouse pointer on an adventure.
Take (remote) control
Remote access software such as TightVNC enables you to control one PC from another. If installed on target victim's machine, you can take control of their PC from anywhere with an internet connection.
Automatic text correction is a godsend text and it isn’t long before people start to rely on it. A few well- chosen edits of the AutoCorrect and AutoText options in Word can cause chaos. Either by turning correctly spelled words into typos or by triggering unwanted and inappropriate text whenever the user tries to type something.
Tape up the mouse
Today’s mice tend to be optical rather than mechanical. Placing a bit of tape will screw up its modern rodent’s sensor just as efficiently.
Make the mouse sleepy
Changing the mouse speed to its slowest setting turns even the simplest movement into an ordeal, while swapping the left and right buttons or reprogramming extra buttons can make the most Ghandi-esque gentle soul want to scream like a wounded gorilla.
Freeze the desktop
This trick is as old as computers themselves, but people still fall for it hook. All you need to do is take a screenshot of your victim’s desktop, hide all of their icons and then replace their wallpaper with the screenshot.