We see them everywhere these days, digital signs by the side of the road telling us about road conditions or that we should prepare to stop or that our local bridge might be closed next Tuesday from noon to midnight. And if you're like me, you've always just assumed that the message on the signs is legitimate and properly authorized.

But what if the sign, instead of reading something like "Ice Ahead" was flashing the message, "Zombies Ahead"?

It's true that in San Francisco or a few other cities, such a sign could be put up by local transportation officials to warn people of an impending zombie march, but even in those places, the more likely explanation would be that the sign was hacked.

And if you're in the Boston area and saw signs hacked in this way, there's always a decent chance it was done by students from MIT. 

According to the blog i-hacked.com, some programmable road signs are easily messed with, largely because they often have unlocked instrument panels, a text-entry system that is easily accessed, and are often protected with uncomplicated, or unchanged default passwords.

Programming is as simple as scrolling down the menu selection to 'Instant Text,'" i-hacked reported. "Type whatever you want to display, (and) hit 'enter' to submit. You can now either throw it up on the sign by selecting 'Run w/out save' or you can add more pages to it by selecting 'Add page.'"

Of course, you probably don't want to do this in plain view of any law enforcement officials, and i-hacked led its post with a disclaimer warning against ever performing this hack.