Thanks everybody for your definitions. They all were great and made me laugh. Douglas not only made me laugh but I also pictured his �tumbarumba� so intensely that I almost decide to become a teetotaler. It was very hard to choose a winner so, as most definitions had something to do with dance, I chose MoodyMoody�s, which I found original and convincing:     

    Tumbarumba is the latest offering from the iRobot Corporation. Their automated vacuum cleaner, the Roomba, has been popular for years. The newer Tumbarumba (from tumble Roomba) will actually vacuum from both the top and the bottom and will clean walls, ceilings, and furniture in addition to floors. If the starting price weren �t $2499.99 for the base model, I would consider getting one for my house. It certainly needs a thorough cleaning top to bottom!

     The real meaning is: tmesis. The introduction of one word in the middle of another, as in Abso-bloody-lutely. It seems to be most common among Australians. There�s also a town in Australia called Tumbarumba. That�s why it�s close to Jayho�s heart.