The hosts file contains a list of known domains and their corresponding IP addresses.
Anything in the hosts file overides a DNS lookup.
... as a line in a PC's hosts file, will tell the browser on that PC to go to 127.0.0.1 (localhost) for any queries to that domain.
The ads will therefore not show, although it may have un-wanted side-effects. The best thing to do is to try it.
I gave the path to your hosts file (assuming Windows 2000 and up) in my post above. Edit it with notepad. It's a file called "hosts" with no extension.
The above trick will block all adsense ads, and possibly with side-effects, but worth a try.
I can't think of any other way of doing what you want to do, whilst allowing you to view ads on your site, if you don't want to do it with cookies.