Open up an Explorer/Finder window and either pick a random folder by clicking wildly, or go to a folder that you use often or would remember the absolute path to off the top of your head. Use that file path as your password, and as long a slashes '/' or ' \' and or":" for Windows users are allowed, it will most likely be the best password you could probably manage without using Password Mangement services like LastPass or Roboform Everywhere, etc.