This Japanese Age Prediction Device is designed to help people on a blind date discover the true age of their partner for the evening. The thing works on our auditory sense, based on the fact that as you get older your hearing starts to fail. Switch on the device and set it to a target age range (e.g. 20s), press the button and it will sound off a mosquito tone. If the person hears it, they’re good.

If they say they’re 20 and can’t hear the tone, they’re lying. And so on up the scale for different ages. Fun eh? Priced at a keychain friendly $10.00 or so. [Via]