I used to have one back in the late sixties and early seventies...

Really nasty nasal sound, would cut through anything! I used to patch it into a Sound City 100 watt guitar amp and terrorize guitar players for fun! Bit of Echoplex, it was quite cool!

Main hit with it was Bowie's "A Space Oddity' where it did a memorable solo...
http://en.wikipedia.org/wiki/Dubreq_Stylophone

By the way, for fans of marsupial bondage, Rolf Harris was it's spokesman in England!