Here's a great little tip for everyone who keeps their car in a garage.

If you happen to be going out to buy a new car, bring your garage door opener.

Here's how I learned my lesson. The lease was up on our van, and my wife and I had decided not to extend it but instead to buy a new van.

Our old van has this cool feature called "HomeLink" which is basically a set of buttons that can be programmed with codes for doing things such as, say, opening up your garage door. I've used it exclusively for our garage door since we first got the van four years ago.

Sunday morning, my wife and I excitedly locked up the house and headed out into the garage to get into the van for its last ride, taking us down to the dealership to turn it in and pick up the new van.

Since we'd been really smart, we actually picked out the car and the options and set up the financing online; all we had to do at the dealership was sign a few papers and off we went.

We stopped to have lunch, christening our new car with curly fries and ketchup as we sat in the back seat and watched the van's "Welcome" DVD on the built-in entertainment system. We know how to party.

We finally came home, and I reached up to open the garage door.

Whoops! I hadn't programmed the new car yet! The homelink button wasn't going to work.

No worry, I'll just use the garage's external keypad.

Whoops! Just remembered that the battery in it died about a week ago, and I hadn't gotten around to replacing it.

Well, I'll just go in the front door.

Remember when I said we locked the house? Yeah, we did that - including the door latch we installed that can't be unlocked from the outside.

We were not getting into the house.

We had to drive a couple miles to get to a store to buy a new battery for the garage door external keypad. With that replaced, we were able to get back inside.

A little humbled, but a little wiser.