Um, your yin(g)-yang is a minced oath for one or another excretory orifice. So yes, you are using it “right”, although I would myself set it in lowercase, and possibly hyphenate it or fuse into a single word: ying-yang, yingyang.
It is similar to — really, equivalent to — up the wazoo, or any number of similar “nonsense” terms for the unmentionable parts. The somewhat reduplicative yingyang also gets used for the same thing that other reduplicatives like dingdong, dingaling, dongalong, pangwang, willydilly, wangerdanger, wangadoodle, and hoohoodilly all also do, and is similar in construction. (Ramalamadingdong may or may not be related.) Sometimes those have hyphens, and sometimes they don’t.
Here is one reasonably citable reference:
Take a term rendered in a foreign language, let’s say “yin and yang.” Have people start mispronouncing (and misspelling) it as “ying and yang,” bring in a slang term for what polite people call the buttocks—“she’s got talent out the ying-yang,” add a rap group called the Ying-Yang Twins, and pretty soon more people will think that “ying” is correct.
Not so “wazoo,” another reference to one’s posterior. As with “ying-yang,” the phrase “out the wazoo” means an abundance. One can also claim that something is a “pain in the wazoo,” and even people who don’t know what a “wazoo” is will understand.
Here, the venerable Oxford English Dictionary weighs in. While it professes not to know the origin of “wazoo”, it says that others suspect it may come from the French oiseau, or bird, through a Louisiana Creole term, “razoo”, for raspberry. (Those with particularly fertile dirty minds may be able to make the connection.) It’s almost exclusively American.
These are North American slang terms, which is probably why they seem “foreign” to you if you are in the UK.