adsense and high cpc cookies

i have read on some chat rooms about using high cpc some people get high cpc on ads.

How do they do this is this safe?

Can advertiser create custom high cpc cookie on end user device to increase ad cpc?

An advertiser can have a deep targeting of specific users to have better conversion rate and more clicks but the only way to find out whom he is targeting is to get this info from the advertiser directly. You can try using different IPs and clicking on ads but this most likely won't bring any result, will get an account banned and if you're super lucky you will not make any profit that is worth all the hustle.