From their Program Policies:
And the email:Prohibited Clicks
Any method that artificially generates clicks is strictly prohibited. These prohibited methods include but are not limited to: repeated manual clicks, incentives to click, using robots, automated clicking tools, or other deceptive software. Please note that clicking on your own ads for any reason is prohibited, to avoid potential inflation of advertiser costs.
If someone was doing this, I'd rather it be admitted, so I know what was going on.Hello Chris,
It has come to our attention that invalid clicks have been generated on
the ads on your web pages. We have therefore disabled your Google
AdSense account. Please understand that this step was taken in an
effort to protect the interest of the AdWords advertisers.
A publisher's site may not have invalid clicks on any ad(s), including
but not limited to clicks generated by a publisher on his own web
pages, clicks generated through the use of robots, automated clicking
tools, or any other deceptive software.
Practices such as these are in violation of the Google AdSense Terms
and Conditions and program polices, which can be viewed at:
https://www.google.com/adsense/localized-terms?hl=en_US
https://www.google.com/adsense/policies?hl=en_US
Publishers disabled for invalid click activity are not allowed further
participation in AdSense and do not receive any further payment. The
earnings on your account will be properly returned to the affected
advertisers.
Sincerely,
The Google AdSense Team
Thanks.