There is nothing quite like painting the town red to celebrate a joyous occassion like a marriage or promotion on the job, but drinking responsibly is another important thing to consider even if you decide to let your hair down. For folks who do not trust cabbies to bring them back in one piece after a hard night of partying, there’s always the Keyring Alcohol Breath Tester that allows you to know whether you need a friend to bring you back or not.

Just hold down the power button until the LED turns green and blow across the top of the grill. If the light remains green, then you’re under 0.05% BAC, and in theory in the clear. If the yellow LED comes to life, then you need to use caution (and probably a bus) as it means you’re hovering dangerously close to the legal alcohol limit of 0.08% BAC. If the red and yellow LEDs come on, then you should throw your car keys into the nearest river and start weaving your way home as you’ve had far too much to drink.

Of course, if you can’t even remember where you’ve parked your car, then there isn’t even any need to purchase this £7.99 device.