Channels you share in common are never hidden... Don't think I need to explain why...
Make sure your nick mode has "+i" with "/mode YourNick +i"... Doing this should hide your channels from others, although it's up to the server to do this or not.
On Unreal severs it’s user mode +p to hide the channels you are on from people that whois you. IRCops can still see the channels you are in, and that you have +p on. ;-) /mode yournick +p