This is my first tutorial, so bash me so I can get better ^^.
Ok, so heres a quick little guide on pranking your friends or anyone else that has a computer with a few icons on their desktop. (If someone has already done this, please don't ban me, I didn't search)
Step 1 - Ok, so heres what a desktop normally looks like (I took off my usual icons, and have just shown a few, but you can do this with as many as you want)
Alright, now press the "Print Screen SysRq" Button, which should be located on the right of the backspace button. You may also use whatever program you use to take screen shots on the computer.
Open up "Paint" and press Ctrl + V. Your picture should show up.
Got to File - Save As - (Whatever you save it as) - Set as background (centered) - and then minimize paint. Once you minimize paint, you can move the icons that are on the desktop. Once you do that, delete the real icons, and the picture should stay up. Since it's a picture, you can't access anything from it. It usually stumps kids and they freak out saying "What the fuck? This computer is whack."
Thats my tutorial, and tell me how you like it. This can get VERY easy over time, and takes about 3 minutes to work it out. You can play around and make it an internet page that won't close or something like that xD.
Thanks guys ^^