A few years ago, most everyone online was introduced to the Otamatone. A Japanese invented, handheld, weird little synthesizer thing. Before you ask, yes, it's huge in Japan. No shocker there.

The idea is that you can make this little finger-organ 'sing' with vibrato by opening and closing the mouth.

Normally, the Otamatone is reserved for ballads, opera, and generally slow-paced instrumentals... but has seen a surge in pop and rock popularity on YouTube. The System of a Down covers being some of the best. Now, it appears to be spreading now to the last pure genre, metal.

While they are pretty hilarious, the funny wears off pretty quick. At least it did for me. On the other hand, your nieces and nephews would love them for Christmas.