Spoofing traffic from google - how to do that?

Hi,
Recently I stumbled upon a site: spoofr net (I can't post links sorry). What this service do is it spoofs traffic e.g. from google. if you don't want showing your affiliate managers where your real trafic come from (e.g. from porn sites) you can use this tool and set fake keywords, pages etc.

Does anyone know exactly the same script which can do the same things but is installed on my website? How this kind of script work?

You work with any ad networks and want to cheat the system approving process and other conditions for work with other companies?

You cannot instruct your browser in this manner.

well there are at least 2 ways to do this.
i think i know how spoofr.net achieves this but it does depend exactly on the tracking script you are using to track the incoming traffic source.