Replacement variable based on user group?

[karabaja]

I am pretty sure this isn't available by default, but I was hoping someone would be able to suggest an easy way to do this, since I don't have much luck with hack requesting at vb.org
The problem I am having is that google adsense is misinterpreting one word used often on my board and that results in a lot of ads which are completely off.
The word "keys" which is used on our board in terms of encryption keys, something related to satellite tv. And most of our members are European.
But adsense spiders are relating that word to Florida Keys. And I get a lot of ads are about Florida Keys holidays, resorts, folorida keys fishing etc.

So what I had in mind is to use replacement variable to change "keys" to "ke*s" or something else but only for guests. So that should hopefully help with adsense dropping off topic ads, and it wouldn't cause inconvenience to registered members.
I am not sure if that would cause any other problems, I am assuming that keys isn't used anywhere in the templates or something.
I saw some censorship hacks which I guess could be used, but I didn't find one that has per usergroup option.
Any help would be much appreciated.

[Wayne Luke]

There is no way to do this without custom code modifications. Replacement variables are assigned to styles, not usergroups. There are no usergroup overrides for these.

[karabaja]

Ok, thanks Wayne Luke, I guess I'll have to make a request at vb.org for this or just use it in replacement variable regardless of it effecting all usergroups.

[karabaja]

Is there a way I could use some php function in a header template or something. With user group conditional and str_replace function. I tried something but didn't work. I am not sure if I got the syntax right or that php code would be executed as such in a template, but maybe someone has a suggestion on how to do it.
I know I should ask for custom modification at vb.org and I did, but I just thought it is worth a shot to ask here as well, as this doesn't seem to me like something that requires a lot of modification, but I might be wrong.