Created by an ad agency who presumably have a vested interest in people getting blotto on New Year's Eve, Havas WW's Buzzed Buzzer only makes a sound when the performer is suitably drunk.

If you want to build your own, Tyler DeAngelo and Sacha De'Angeli have created a site with fairly detailed instructions and schematics, but there's one important improvement you'll want to make. Namely, making the noisemaker actually stop working when someone is drunk, which will in turn make your New Year's even shindig slightly less insufferable when the clock strikes midnight.

New Year's Noisemaker Breathalyzer Makes You Extra Annoying When Drunk

[Buzzed Buzzer via Laughing Squid]