Bonephones?

A colleague at work was showing off his new toy, a pair of Bluetooth headphones. I say "headphones", but actually they don't contain speakers as such and work via bone conduction. Does that make them "bonephones"?

Anyway, he was merrily listening to them until the rest of us pointed out that we could all hear his music in typical over-driven tinny earphone fashion. It seems that they're actually pretty rubbish at the bone conduction part - he claimed that the sound he was hearing in his head was quieter than the sound produced by the transducers being driven hard enough to act as speakers. Weird.