We all know that Adsense doesn’t like inflating impressions or clicking our own ads, but sometime while testing our websites, it become absolutely necessary. At the same time, we don’t want to risk our Adsense account for any invalid activity, So here is a piece of simple solution to this problem, Just add google_adtest = �on�; to your ad code.
For Example:
[code]google_ad_client = pub-xxxxxxxxxxxxxxxx;
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = 468×60_as;
google_ad_type = text;
google_ad_channel =”;
google_adtest = on;[/code]
Now any impressions or clicks will be ignored by Adsense, So you can work on your website without any hassles. Your allowed to make this change in your ad code even though Google’s Policies doesn’t allow. Just in case your uncertain, please contact Adsense Support Team
Credits: Daniel

wrote, on October 4th, 2006
That is pretty interesting… how did you find that out? Does Google allow this, because I thought that TOS doesn’t allow you to modify the code in anyway? So, I am wondering though… if this modification came from Google directly? Please tell me more about how you figured out how to run Adsense in Test Mode.
wrote, on October 5th, 2006
Hey, this is new to me too. I didn’t know that. Google should told us that, right?
wrote, on October 5th, 2006
Garry: Actually I have contacts inside AdSense, who leaked this information to me. I don’t want to disclose his name because it would risk his job
Rhazes: Yeah, they should have informed us about it, but unfortunately they haven’t, maybe they will official disclose more info regarding this in the upcoming days
wrote, on November 24th, 2006
just use the adblock extension using firefox and block google ad’s server..it’s easier.
wrote, on November 24th, 2006
Bloganything: But That’ll block all ads
wrote, on March 9th, 2007
It’s easy, thanks.