Some companies issue "China" Laptops to their executives that they must discard after visiting China. Now I believe we all need throw away laptops and cell phones and Facebook accounts for any sort of international travel.
Fact is: I don't do Facebook, nor any other Facebook product, so I'm really not able to hand over any such credentials.
With TSA/Customs you need to be truthful. If you don't have an account say so. If you have one and say you don't that's a felony.