How to find out if two people are mutual friends?

[Lucas C]

If two of the people hid their friend's list from everyone else(they are both my friends) on facebook, Is there any other way you could find out if they are mutual friends? If you know what I mean, usually when two of the people hide their friend's list, you can't see if they are mutual friends or not. So does anybody know is there is another way? 10 points for best answer!

[Y07]

For example if a & b are your friends, If you view the friend list of "a" then you will get to know.

[Rico]

If only 'friend A' has their friends list hidden, then seaching the list of mutual friends on 'friend Bs' list will show 'friend A'

If you can't see the list of friends for either person, then you'll just have to ask one of them. If you see them commenting on each others statuses then thats proof that they are mutual friends