An in-car necessity.

Unless you’re ready and willing to get out and throw punches, you’re pretty powerless on the road. If someone cuts you off or tailgates you, there’s really nothing you can do except lay on the horn and hope they get the message.

That said, if you’re really brave, you can also try this.

The woman below decided that, if she was going to be stuck behind someone not meeting the speed limit, she was at least going to let them know about it — and now, she’s introduced her device to the world, leading to every single person watching the video (me included) to want one installed in their car.