From Trader Vic's:

"Originating from Papua New Guinea, the design of our mask logo was introduced in 1951 and since has been the symbol of Trader Vic's known around the world. Notu, is a Papuan language spoken in the 'tail' of Papua New Guinea. Our Mini Notu holds up to 2 ounces."

There is also a full-size mug of this same design produced in this color-way or in a dark gloss brown.