i, too, have thought about it recently. something to mark a change. i even have a design in mind. and i'd put it on my upper arm - where it could be seen - but not all the time and not too big.
my wife and kids and boss and friends and co-workers would all be totally shocked. they would all think it was completely out of character. maybe that's a good reason to do it! like saying - you don't know as much about me as you think.
"That you are here - that life exists, and identity; that the powerful play goes on and you may contribute a verse. . . What will your verse be?" Robin Williams as John Keating in "Dead Poets Society"