Kisai Breathalyzer Watch
While we wouldn't recommend it for determining if you're good to drive, the Kisai Breathalyzer Watch ($100) could make for some pretty interesting bar games. After breathing into the side of the watch, an LED backlight responds, turning green if you're sober, yellow if you're tipsy, and red if you're drunk — as well as displaying your BAC percentage. The stainless steel watch has an adjustable band and a USB-rechargeable battery that lasts for a month on a charge. It also displays the time, of course, so last call won't sneak up on you.