Many people don't expect any emergencies to happen in their life, and if they do, they expect to deal with it when it happens. If you are one of those, I encourage you to change your mentality on this subject, because at some point, you WILL have an emergency. You need to have this money where it is barely accessible, where you actually have to work to be able to use it. And by work, I mean, pull the money out of the bank, or something that will inconvenience you to use it. The hope is that this money always stays put, and that you never need to dig into it.
With that said, I encourage you to take a portion of your tax return (if you are getting one), and put it back for a rainy day. You'll feel much better knowing that you've accomplished this, and if that emergency ever arises and you need it, you'll feel even better.