Many times a month we all get those “do this and this happens…”, “this video shows…“, “Facebook have done this…“. But he vast majority are pointless wastes of time.

Why Viral:

These messages spread so quickly because there is an implicit trust in the system; they’re called Friends for a reason.
I got fooled by a (nearly) harmless one today, SIM card names. I was suspicious though…

So why do it? Well, tricky. The harmless ones can be funny but for those looking to make ‘free’ money putting money making (payed per click or even phishing) schemes into these messages makes sense. We’re used to them in email but here our friends spread the nasty stuff of their own free will and without really checking.
There have been the odd really nasty item too to watch out for.

Advice:

If you’re not sure of the validity, do a search! Google can be a great source of information. Or ask an IT friend.
Best source I have at the moment is HoaxSlayer or more specifically their Facebook page!