At the same time, I'd like to make the case for eyebrows as a motif --- not in place of mustaches but along with them (but on their own, not together with mustaches; that would be too much). They're hair. They come in lots of fun styles. They're manly --- or womanly. And they're expressive, even without the eyes they grace.
Eyebrows are as versatile as mustaches are as a design element. Thus, I contend, anywhere you might playfully place a decorative mustache you can equally --- and perhaps even a touch more meaningfully --- place a set of eyebrows.
I rest my case.
Until next time --