'Leitz Catalogue Chinese' made sense in the days of telegraphic ordering, because you can convey more meaning with 5 letters than with 5 numbers. Arguably it's harder to make a mistake, too.
Some code-words have obvious origins -- ELMAR, EKURZ, ELANG (Elmars in 5cm, 3,5 cm short or 'kurz', 9cm long or 'lang'). Others are just plain weird: NOOKY is indeed a favourite, but a plain NOOKY is for an Elmar and NOOKY-HESUM is for (I think) the Summitar. And I've always wanted to see a 'spider' copier in the window of a camera store so I can go in and say, "How much is that BOOWU in the window?"
Cheers,
R.