To do a reading, simply open the sensor cap on the edge, press the "alcohol" button, and give it a 5sec blow (wait 15ish mins after sipping any booze for the most accurate reading). The right side of the face's screen will then light up in a specific color to indicate your level of intoxication: green means sober, yellow is buzzing, and red suggests you should be calling a cab. Or a pedi-cab. Or a dude riding a unicycle with a basket attached to it. And to help estimate whether you'd successfully pass a sobriety test, it's even stocked with a game that tests hand/eye coordination and reaction time.