I am quite happy to accept this as the origin of oojah and {oojah + anything else}
1917 Washington Post 22 July 10/1 An entirely new crop of slang has come into use in the British army during the past year... Oojah may come from the East, with ‘cushy’ and ‘blighty’ and ‘hondook’.
As it is colloquial, standardised versions and spellings will not exist for some of the more exotic versions.
oojah, n. colloquial.
A thing whose name one cannot remember, does not know, or does not wish to mention; (by extension) a useful implement, a gadget.
1917 Punch 24 Jan. 52 (caption) N.C.O. ‘Here! Just grab the oojah an’ dash round to the tiddley-om-pom for some umpty-poo!’ Private..learns later that he was expected to fetch a bucket of coke from the stores.
Etymology: Origin uncertain. Perhaps shortened < a formation similar to whatchamacallit n. (compare what-d'ye-call-'em n.); compare oo pron.2, but perhaps either < a nonsense word used as an exotic-sounding name (see quot. 1901 in etymological note), or < Urdu and Persian ḥujjat argument, pretence, excuse and its etymon Arabic ḥujja argument, pretext (see etymological note and compare oojah capivvy n.).
oojah capivvy = oojah n.
Etymology: Origin uncertain. Perhaps < Urdu and Indo-Persian †ḥujjat kāfī fīhi, literally ‘the argument is sufficient’, there's no more to be said about it ( < ḥujjat (see oojah n.) + kāfī sufficient ( < Arabic kāfī sufficient) + fīhi in it, about it), ... Compare modern Persian ḥujjat kāfī that's all there is to it. Compare ..with the form in -cum- compare oojah-cum-spiff adj.
1917 Lines (Divisional Signal Co., Royal Engineers) Nov. 13 Things We Don't Expect... A civi to understand the order ‘Take this ujakapivi and go to the oojah and bring some what's it.’
1992 Hobart Mercury 8 Aug. There are several of Ms Bosanky's turns of phrase that are pure Downunder. For instance, ‘hoojah-kapippy’..or a ‘whatsitsname’ euphemism.
oojah-cum-spiff
Etymology: Perhaps an alteration of oojah capivvy n., after cum prep. and spiffy adj.
Fine, all right.
1930 P. G. Wodehouse Very Good, Jeeves i. 25 ‘All you have to do,’ I said, ‘is to carry on here for a few weeks more, and everything will be oojah-cum-spiff.’