How To Hide Mututal Friends On Facebook.

Login to your Facebook account and click on ‘Account’ at the top right.
In the drop down menu that shows up now, choose ‘Privacy Settings’.

Click on ‘View Settings’ under ‘Connecting on Facebook’.

In the page that appears now, hit ‘Everyone’ (usually the default) parallel to ‘See your friend list’ and choose the appropriate setting you desire. If you are looking to hide it from everyone (including your beloved friends) choose Custom and then ‘Only Me’ under ‘These People’ in the ‘Custom Privacy’ menu