First fo all, sorry for my bad English: I'm not a native speaker.
Also, this is my first instructable, so, be doubly patient ;)
This is a very simple joke you can make to your friends or colleagues.
They will find their desktop completely frozen, except for the mouse.
The victim will be unable to click on any icon or on the taskbar.
I believe this is doable on Mac and Linux systems as well, but this example is based on Windows systems.
What do you need is just your victim's PC and any image editor (Windows Paint is enough).
Oh, yes, you need also to keep an eye to the victim, before making things worse (see last steps).
Step 1: Distraction
First of all, you need to find a way to let your victim leaving his desk (e.g.: coffee/cigarette break, toilette, etc.).
Step 2: Take a Shot
Now that you have the control of your victim's PC (hoping he's one of them that doesn't lock their PC each time he leave the desk), if you can, close all applications, or at least, minimize them, in order to see the whole desktop, then press PRT SCR key on the keyboard (take a screen shot, in a nutshell).
Your victim's desktop is now in the clipboard and you need to save it as an image. To do that:
1. Open Windows Paint (or any image editor). If you don't know where is it, just click START and select RUN, then type "mspaint" and press enter (I think is some version of Windows, you should type just "paint").
2. Once Paint is open, just press CTRL-V (or click Edit->Paste) to paste the screen shot.
3. Save the image (File->Save) as bitmap (bmp).
Step 3: Background
The image you just saved, need to be set as a background of the desktop.
1. Right click on the desktop
2. Select properties
3. Open "Desktop" tab
4. Memorize the current image (to rollback the joke ;)
5. Click "Browse"
6. Locate the just saved image
7. Select this image
Of course, you will notice nothing, unless you move some icon
Step 4: Hiding All
Now, we need to hide all icons and the taskbar.
To do that:
1. right-click again on the desktop, select "Arrange icons by" and then uncheck "Show desktop icons"
2. if the taskbar is locked, we need to unlock it: right click on an empty spot of the task bar and uncheck "Lock the taskbar"
3. On the unlocked taskbar, sizing handles are visible: move the mouse pointer to the thin bar that appears along the top strip of the taskbar, until the mouse pointer turns to a two-headed arrow.
4. Hold down the left mouse button and drag that top edge down until the taskbar disappear.
Check here for more information and tips about the taskbar: http://www.coolnerds.com/XP/Taskbar/xpTaskbar.htm
Step 5: Conclusions, Rollback, Improvements and Advices
The joke is done.
If you try to excercise a bit by yourselves, you will be able to do everything in less than a minute avoiding to get busted ;)
To roll back, just review all the steps, restoring the right background, enabling all the icons and resizing the taskbar (sizing handles are still visibile and availables at the very bottom of the screen).
1. you could enable taskbar autohiding to a better result (depending how much clever could be your victim)
2. you could keep open some windows before taking the screen-shot
1. be sure to know how to roll back, to avoid troubles (especially if you plans to do that at work)
2. if you plan to do that at work, be sure to find the right target: some stupid people could go straight to IT dept., bosses, etc :S
Enjoy it! ;)