You’re at a party, set your drink down, and turn to talk to someone. When you look back, a strange bearded man is drinking your beer. Not cool, bro.

CanStamp has you covered. Simply press the stamp into the side of the beer can to indent words like “IN USE” and “MINE.” This keychain-sized stamp will change your world.

The product is a mere $7.95—a small price to pay for something that could save you from that weird lip sore that your friends keep passing around.

On the other hand, as Gizmodo points out, “debates over ownership could flare up if more than one person brings the $8 CanStamp to a party, so you might want to skip this one until they come out with a version you can personalize with your name, or a more specific threat.”

Watch the video below to see CanStamp in action.

[via Gizmodo]