There's something that sounds dirty about this, Subway is about to start spraying its DNA all over you. They just started rolling out a new security system that sits above the door and contains a vat of a synthetic DNA substance.

Whenever there's a robbery at a Subway, an employee presses a button, and the stuff sprays all over the guy as he leaves. It's invisible to the naked eye, but it stays on your skin for up to seven weeks and doesn't wash off.

It'll show up under a black light, so that cops can check a suspect for it and prove he either was or wasn't the person who knocked off the Subway. Each store has its own unique DNA, just to make sure there aren't any false positives.

For now, Subways in Knoxville, Tennessee are getting this security system, it's going to spread to thousands of them nationwide soon.