AntiSnoopy will obsfuscate the domain history that your ISP (if in the UK) now stores and makes available to a vast number of people under the so called Snoopers charter.
You just run the app and let it contact a number of randomly constructed URLs which when aggregated by your ISP will mean that the list they collate includes a lot of false stuff.
Version 1.4 introduces the ability to visit the same generated domain a number of times so to help avoid the exclusion of the domains by a frequency analysis.
It is recommended that you do not leave this running in the background without stopping it first (via the button) and also that you do not allow it to use mobile data unless you keep an eye on its data usage.