Similar to joke insurance, facebook insurance is the mutual agreement to like/ comment on a friend's facebook status regardless of what it is, it is usually used to lessen the embarassment of having a really unsuccessful/boring status.
A friend will like/comment on your status, and you return the favour when they post a status, regardless if you have any interest to it.
Sharon is sitting down
*John likes this*
Person 1: Whoa Sharon and John totally have facebook insurance...
Person 2: Totally