A new bug was discovered yesterday that is affecting a lot of iPhone users (I need to check mine)... if someone Facetime's you they may be able to instantly see what your front facing camera sees and hear what your microphone is picking up. Even WITHOUT you accepting the call. Not gonna lie there have been times that I've been sitting on the toilet and gotten a Facetime request... I decline it but imagine a friend trying to Facetime you while you're doing something you don't want them to see but they see and you have no idea.
Also makes ya be careful to not talk sh*t about the person calling you.
*Facetime call comes in
"ugh... I hate talking to this person"
*they know now lol
Look below for a video of it happening