Seriously mind boggled facebook question?

[Kourtney]

If you are friends with someone on facebook how can u still be their friend but they can hide everything including pics so that u can't see it ? Most weirdest thing was before Idk why setting she made it to but after she accepted my request I couldn't see any pics and I told her that then she said try again like WTF I could see her pics what setting did she make her account anyone know