That’s one of the oldest Black Hat SEO tricks in the book, and Google already knows about it.
Go ahead, tell your client to mess with Google and he’ll end up being nothing in the Internet. Yes, Google rules the Internet… and we all have to abide by its rules.
Also, ask your client to ask his friend for the URL (URI) of his site so you can check out the code and see for yourself how he ‘supposedly’ pulled it off. If he did, he might’ve probably pulled it off more than 10 years ago.
Have your client’s friend also provide some web analytics of his site, if he really got shot to the first page of Google’s search results, the increase in traffic should be very noticeable.
Also, by knowing the URI of your client’s friend you can see what market he’s actually trying to reach, if he has a business that sells "custom silver patches for overheated tractors during full moon and platypus growing season" then he did probably make it to the first page of Google… because there’s no one in the entire planet with a website like that, only he, so there’s no competition, hence, the first place.
See what I mean? ^_^