Well, I remember once needing to use that function to recover a password I had forgotten. If i hadn't put real information as an answer to the question, I'm not sure how I would have been capable of answering it..
Now I associate a friend I grew up with the site and fill it out as if I was them. Now I can say "ING -> Mike" and I know which Mike and what their info is but it doesn't mean anything to anyone else.
And now that I've said this on a public forum (a little googling is all it takes to identify me) I will have to change it to something more obscure...