Yes, keberoxu, although I had heard the word "wossname" on British TV shows, it never really registered in my brain as a word until Terry Pratchett used it.

In Oz we have whatsits, whatchama'callits, whoozama'jigs, thingumy'jigs, thingummy'bobs - well, the list goes on and on. (The ' mark shows the start of the accentuated syllable, in case you are wondering. They aren't spelled that way.) Thingy-poo is also a favourite of mine.