if your friend goes to the bathroom or something, this is the best trick which will confuse them for a long time... Best COMPUTER PRANK
when they leave,
bring up the desktop and press the key on the keyboard that says "Prnt Scrn"
open up the paint application and right click and paste.
a pic of the desktop will be pasted, then save the file to "my pictures" or something
Right-click on the desktop background and select "Arrange Icons By",
then select "Show Desktop Items" to uncheck it. If your friend's computer doesn't show the
"Show Desktop Items" option, you may move all of their desktop icons
(user created ones, not the Recycle Bin, etc.) to a different folder.
You may also hide desktop icons such as "My Documents", "My Computer",
"Internet Explorer", etc. by right-clicking on the desktop, selecting
"Properties", clicking on the "Desktop" tab, and then clicking on the
"Customize Desktop..." button.
then go to the file where you saved the picture of their background and right click and press"set as background.."
then right click on the bottom toolbar and go to properties. Then check the box called auto hide.
then.... watch as your friend attempts vainly to click mozilla or itunes a million times...lol noobz