1. Mouse ball mayhem. This trick is simple but effective. All you have to do is remove and hide your colleague's mouse ball and then try and hold in your laughter as they start cursing their computer. With any luck the victim won't think to flip the mouse over and will have to call tech support.
2. Switching mouse buttons. Again this is an easy trick to perform. Go into mouse settings on your workmate's computer and swap the left click with right click. You can also increase the April Fool's Day hilarity by slowing down the double-click speed.
3. Wallpaper screenshot. This prank is a classic. Take a screenshot of the victim's desktop and then set it as their wallpaper. Next set the Windows taskbar to auto-hide, navigate to the Control Panel, click on Taskbar & Start Menu and select "Auto hide." Then just sit back and enjoy the suffering.
4. Infrared mouse confusion. This is the modern version of the old mouse-ball-removal trick. Put a piece of tape over the laser sensor on an infrared mouse and wait for your workmate to go ballistic.
5. Messing with MS Office Autocorrect. This is a simple way to punish your colleagues' over reliance on MS Office's Autocorrect feature. Just go into Tools, Auto Correct and add your own alternative spellings to commonly used words such as 'because' and 'again'. Hopefully your workmate will be so used to using Autocorrect that they won't notice your cunning ruse until it's too late.