Explanations/etymology also appreciated!
For Joe Shmoe, it means a very average or below average person. It’s a derivation of the practice of using “shm-” to dismiss something (eg “Practice shmactice. We’re already perfect”).
And “John Smith” is meant to be the most average name or person imaginable, so they have the “most common” (citation needed) first and last name as well.
Hm, well about 40% of our population is named Nguyễn. I don’t think there’s an equivalent expression, but I’d choose Anh Nguyễn. In addition to being a name for both genders, ‘Anh’ just means something like ‘sir’ or ‘older brother’.