These security questions decrease the security of our accounts by providing a second way in, allowing an attacker to bypass the password protection. That's if you provide correct answers to the questions - and if you make up nonsense nobody can guess, you won't be able to remember it, defeating the purpose.
My standard way of dealing with them is to make up a second password to use as the answer, so it's equally secure, but also still easy to remember. Unfortunately Apple defeats even this by requiring each answer to be different, so I would also have to think of a third and fourth password, making it even harder to remember.
They should be referred to as INsecurity questions, and they should be abolished. My recommendation is to type random letters and numbers, give a fake email address (since it can't be the same as your iTunes username), make up a birth year (but don't make yourself too young), and hope you never forget your password. Write it down if you need to - it's still more secure than all this crap.