Clicks on you own adsense, Post aduct content on site where adsense present or place adsense block where aduct content present, Do to tell you friends or relative for click on your ads.. for you may read on adsense blog..
I'd be guessing, but any effort by either you or someone else to artificially inflate your page impressions or click rate - that's what I'd class as invalid activity.
Clicking on your own ads is not an invalid activity its totally prohibited. just make several click and you will be definitely be banned.