Dateline - Any workplace in the U.S. with a HR Department
Topic - Can HR people have good friends in the workplace?
Capitalist Conclusion - You should be able to, but it is tough.  Proceed at your own risk...

If you've worked in a HR position at the same company for more than 3 years and opted to have a normal set of good friends in the workplace (the kind you are repeatedly seen at lunch with), you fall into one of three categories:

1.  You've felt the sting of a co-worker friend ask for, or allude to, confidential information in their day-to day conversations with you (testing..1..2..3..).

2.  You've felt the sharper sting of co-worker friends a) attributing confidential information they share with others to you, or b) sharing confidential info and having the recipients of that information assuming they got it from you, since the co-worker in question is widely believed to be your best friend (just as dangerous).  PS - you may not know this is occurring as in 2b...

3.  Employees outside your circle of friends have a lower probability of coming to you with concerns or items they need your help on, either because they don't like one or all of your workplace friends, or they feel out of the loop.   You won't likely know this one is occurring either...

You're damned if you do and damned if you don't.  If you don't have friends in the workplace, you don't get what you need socially from work and you may be considered aloof and unapproachable.  If you do have friends in the workplace, you can get scorched worse than Fire Marshall Bill (pictured above) by the rumors and undercurrent of alleged favoritism in the organization (the Fire Marshall Bill skit would go like this - "let's just say...you're a HR Manager with friends who like to gossip.. You go to lunch and let it all hang out about Tommy in accounting, and BAM!!! Destruction!!)

So what's the best solution for you, the HR Pro?  Take care of yourself, but take care of your reputation.  Have a small group of workplace friends that you can trust, and treat their reputations as seriously as you do your own.  Let them know your concerns and expectations.  If an employee outside of that circle comes to you with an issue, give them 2x the service and urgency you would give to your friends, to show you're above and beyond reproach.  And if your friends violate the trust, eliminate the visible affiliation with them in the workplace.

I know, I know, it shouldn't have to be like that.  But it is.  HR people have access to a lot of data, and as a result, you're held to a higher standard.  Welcome to your personal version of Employee Relations.  The goal?  To advance your career without looking like Fire Marshall Bill after a chemical explosion...