There were many made-up words in my family. As I discovered to my chagrin in elementary school that many were not "real" words, I quickly edited them out of my public speech. One word I assumed for decades was also made-up was grex. Grex was used in our family to mean grumpy or cross; a common admonition was "don't grex and complain."
To my delight I found grex a few years ago in the OED, defined as my family used it. Its root is Old German, which makes sense as German was still spoken in my mother's paternal grandparents home when she was growing up.