When cats and dogs want people to know when they are happy, they wag their tails. Some of us humans have now decided to not only copy that idea, but to let the world know about it.

In what is thankfully just a proof of concept at the moment, a Japanese firm has designed Shippo, a robot tail. The person wearing it also puts a sensor on their head that measures electrical activity on the scalp and sends signals to the tail via Bluetooth.

It’s effectively a binary scale: a calm mood leaves the tail drooping, while excitement, happiness or any other emotion that increases brain activity means the tail starts wagging.

Manufacturers Neurowear say it’s just a demonstration idea at the moment, but they might put it on sale if there’s demand. If you’re thinking that sounds like empty talk, think again: the company already sells Necomimi, a set of cat-like ears that work in a similar way, perking up when the person is excited. It’s described as a minor hit for American cosplay fans and bachelorette weekends.

The company also says Shippo could be hooked up to social media sites via geotagging, meaning your friends and followers can get automatic alerts of exactly where you got excited. I guess anyone who chooses to use this feature brings the risks on themselves, but you’ve got to feel for the sucker who narrowly avoids being hit by a car only to have the world informed that they got excited outside a particularly inappropriate location.