Not that your tattoo need announce your identity explicitly: CEO of Twitter and Square Jack Dorsey, 41, told the New Yorker magazine that his large S-shape forearm tattoo symbolizes the form of the collarbone, the integral symbol in calculus and the violin’s f-hole.

A natural wood color, the cello has an asymmetrical carbon fiber tailpiece with a cutout design and an f-hole labeled "Antonio Domenicelli Fecit en Ferrara 1714."

Then the finer skills came: mastering the scroll, the c-bout, the f-hole.

In calculus the most recognizable icon is the integral sign: Its graceful lines are evocative of a musical clef or a violin’s f-hole — a fitting coincidence, given that some of the most enchanting harmonies in mathematics are expressed by integrals. 

A moth flies out of the guitar's F-hole, and the brothers watch it flutter around the room.