Is there a way I can tell google not to follow external links ( pointing to other sites) without letting other know.

I know you can disable outbound links by putting rel=nofollow or something in robots.txt. But that's something others can see as well.

I'm just wondering if there's a way to tell google not to follow those links without letting others know that... like a setting in webmaster tools or something similar

( there's definetly one way. I could set an exception in my conf file for my server to check the user agent to be "googlebot" and then serve a different version of robots.txt. So that when a different user would check that link it would return a different robots.txt thant the one served to googlebot. However I'm not too sure google would be too happy about this)

Thank you