This requires access to your friend's PC. You take a screenshot of your friend's desktop, set it as their wallpaper, and move all their desktop icons into a separate folder (don't delete them; that would be over the line). Then hide the remaining folder in your OS, which means all they see on the screen will be the wallpaper. When they try to click on the icons, swearing and astonishment will likely ensue.
Those who use Windows have probably, at least once, experienced the Blue Screen of Death (BSOD). You can install the Blue Screen of Death screensaver to simulate that, and scare the bejesus out of your co-worker. The download comes from Microsoft, so you can be sure it won't hose your Windows computer with a real BSOD.
3. Vaseline on the doorknob
Crisco will also work just fine. Slather on a little bit, and get ready to crack up as your victims are denied entry.
4. Buggy toothpaste
Place a raisin in the end of the toothpaste tube. When someone squeezes out the paste, he/she 'll get what looks like a bug along with their minty tarter control glob.
5. Change the clocks 把表调快
After your roommate (or boyfriend or whoever) goes to sleep, change all the clocks in the house by an hour…or four. There's nothing more infuriating than taking a 4am shower just to realize you've been punked. Oh and make sure you set the clocks ahead and not back. You don't want anyone to show up late to work and get in an serious trouble, right?
6. Cake prank 假蛋糕
Find a box about the size of a cake. Then cover it with frosting, making it look like a cake. Then put it out in the office kitchen, or wherever people leave free food. Sit back as one of your co-workers tries to cut a slice.
7. Walky-talky on your pet
Take a little walky-talky on your pet or hide it somewhere near where it is laying. Walk off to a safe distance where you can keep yourself hidden from others with the other piece. As soon as someone tries to pick up or pat on the back of your pet, say in a gruff voice, "I hate you doing this to me." See them jump with fright and shock.
8. Toothpaste Oreo 夹“心”奥利奥饼干
You buy a box of Oreo cookies and White toothpaste, scrape out all of the white icing off of the Oreo. Then fill the middle of the Oreo with the white toothpaste! Leave them out somewhere so whoever you're pranking can see them. Have a garbage can out and ready for them to be spit out!