Clicking on your own Adsense ads may happen to anybody. But what does Google do if they found out that you have clicked on your own ads.Generally Google don’t take it seriously and it understand that accidental clicks sometime may happen to anybody. But if you see a suspicious clicking activity on your account you should report it to Google.
Anyone can bombard your account with tons of clicks for the termination of your account. Suppose your average CTR is 3-4 % and suddenly one day it rose to 20-30%. If this look dubious to you, Report your invalid click activity to google here.
An active discussion on the issue can be found out here