Any sufficiently advanced technology is indistinguishable from magic.
– Arthur C. Clarke
Here's a magic trick to surprise your friends with. What they will see is this: you are at the Google homepage, and you casually ask someone to watch the Google logo. Then, you move two of your fingers to completely cover the "o"s in the Google logo. When you remove your fingers, to much surprise, the letters "o" will be missing from the logo. Now you ask your friend to move her fingers over the missing "o"s. After your friend removes the fingers, the logo will be complete again!
The trick here? It's not really the Google homepage you and your friend are looking at – it's a fake page (darkartsmedia.com/Google.html). And when you click on the page, the letters of the logo will disappear after five seconds. Clicking again will make them reappear after five more seconds. So when you move your fingers to cover the Google logo, simply click anywhere on the page, and wait a bit before you remove your fingers… and when your friend covers the letters, you click again. (A third click, by the way, will change the page to an actual Google homepage so you can perform searches to "prove" the page is real.)