As an addendum: I've just had a browse through my dictionaries and 'doobry' doesn't appear anywhere, although I don't have a dictionary of current usage. So I thought that maybe it was a local phenomenon. Then I did a quick check with Google and got about 3,290 hits, including a Usenet newsgroup called alt.doobry.
Perhaps the most relevant comes from here:
"Following my article about words like thingummy which are used as vague terms for something unspecified, another correspondent wrote to ask the origin of the word doobry — another synonym for a thingummy.
Jonathan Green’s Dictionary of Slang gives three possible spellings — doobrie, doobry and dubry — and says the word originated in the Army around the 1950s, and gained a new lease of life, thanks to the entertainer Kenny Everett, “who used it frequently in the 1970s-1980s”. But Jonathan Green supplies no etymology."
Perhaps the most relevant comes from here:
"Following my article about words like thingummy which are used as vague terms for something unspecified, another correspondent wrote to ask the origin of the word doobry — another synonym for a thingummy.
Jonathan Green’s Dictionary of Slang gives three possible spellings — doobrie, doobry and dubry — and says the word originated in the Army around the 1950s, and gained a new lease of life, thanks to the entertainer Kenny Everett, “who used it frequently in the 1970s-1980s”. But Jonathan Green supplies no etymology."