Q From Neil King, UK: What is the origin of the Cockney expressions drum and gaff (gaffe?) for one’s place of residence?
A The origins of neither of these is well enough established for anyone to be able to give you a really firm answer. However, there’s a good case to be made for an origin in the Gypsy (Rom) language, Romany.
One possible source for drum might lie in some idea of its being an enclosed space, like the inside of a drum. But it’s suggestive that from the late eighteenth to the late nineteenth centuries the same word was used by English Rom for a road or street — it’s thought to come from Greek dromos for a road. It is very possible that the word shifted sense somewhat to refer to a place of habitation alongside a road.
The second one is certainly gaff (not gaffe, which means a blunder or embarrassing mistake; see blow the gaff and other senses). This comes almost certainly from the use of gaff in the eighteenth-century to mean a fair, and later a cheap music-hall or theatre (as in the famous penny gaff). Again, this probably comes from a Romany word, this time for a town, especially a country town that holds a regular market, where such a fair might be held.