There are two simple ways that can protect you from clicking on your AdSense Ads accidentally.

Disable Your Browser Javascript

You can stop Google Adense ads from showing in your Google AdSense site while you are working on it by disabling your browser Javascript setting. The following steps will show you how you can disable Javascript in Internet Explorer and Firefox.

Internet Explorer 3.X
1. From the menu bar, select the Tools, then click on the Options.
2. Select the "Security" tab page
3. Uncheck "Run ActiveX scripts" to disable Javascript
4. Restart the browser

Explorer 4.x
1. From the menu bar, select the Tools, then click on the Internet Options.
2. Select the Security tab page
3. Select Custom and click on the Settings... button
4. Select Disable under Active scripting to disable Javascript
5. Restart the browser

Explorer 6.x
1. From the menu bar, select the Tools, then click on the Internet Options.
2. Select the Security tab page
3. Select Custom Level... button
4. Select Disable under Scripting - Active scripting to disable Javascript
5. Restart the browser

FireFox
1. From the menu bar, select the Tools, then click on the Options.
2. Select the Content tab page
3. Uncheck Enable Javascript to disable Javascript
4. Restart the browser

Edit the Hosts File In Your Computer

You can also block Google AdSense Ads by using another simple trick. Open the host file in your PC with Word Pad/note pad and add the following entry in the host file of your PC:
? 127.0.0.2 pagead2.googlesyndication.com

Once you save the hosts file and restart your browser, you will not see the AdSense ad while you are working on your AdSense web site.

You can find the hosts file from the following directory of your PC:
? Windows 95/98/Me (c : windows)
? Windows NT/2000/XP Pro (c : winntsystem32driversetc)
? Windows XP Home(c : windowssystem32driversetc)

Please be aware that if you've disabled the javascript in your browser, any program that is relied on Javascript may encounter problems. If you've disabled the AdSense ad by editing your host file, you would not be able to view any Google AdSense Ads from any Google AdSense site. So it is highly recommended that you undo the changes when you finish working on your site.