Re: should i?...
If you think he has potential (according to his resume), then you can give it to HR and just let them know that you don't actually know him or what his work experience is like since he is a friend of a friend, so HR can then do whatever tests they need to do and won't just rely on you as his reference, therefore keeping yourself clear of any blame. You can also let your friend know that you forwarded the resume to HR and are leaving it up to them to decide if he is a good candidate or not.