I met a long-time couple recently, and I frequently heard the wife calling her husband "Mensch."
As an example, at one point she asked
"Was ist das, Mensch?"
and at another
"Ach, Du Mensch!"
It was said in an exasperated, yet still clearly affectionate, manner.
(I'd seen it translated in other contexts — e.g., in a libretto for Alban Berg's Wozzeck — as an insult; hence my confusion as to what the word means.)