There is nothing more embarrassing than having a friend point out that your fly is down. It happens a lot when we’re young because we’re stupid and can’t be bothered to zip up before leaving the house. I wrongly assumed I would learn better as I grew older, but a new DIY tool will make sure that you’re always zipped up before heading out.

The ever brilliant Randy Sarafan of Instructables has created what he calls the Discrete Pants Fly Checker. It’s a little device you can build yourself that will check whether or not your fly is down after a visit to the restroom. Here’s how it works:

By pressing a button located in the watch pocket of your pants, a small pager motor alerts you to whether or not the zipper is up. Basically, the zipper of the pants was enhanced with two strands of conductive thread which form a complete circuit when bridged. A small circuit board with a battery, button and motor attached then snaps into the watch pocket. Finally, when the button is pressed, and the zipper is closed, the circuit is completed and the motor vibrates.

Got that? It vibrates if you’re all good and doesn’t if you need to awkwardly turn around to fix the problem while pretending that you’re checking a text. It’s a win-win for everybody even if your friends all knew what you were really doing. They just wanted to see how long it would take until you noticed yourself.

If you want to learn how to make your own, check out the easy to follow instructions over at Instructables.

[h/t: Gizmodo]