I had my left ear pierced on my 21st birthday. I never got a tattoo (I almost got one while in the Navy), because while you might think something is cool when you young, I figured decades later it might not be so cool.
Yes, well it was certainly like a trend to mark adulthood; although these days I reckon it's even more widespread among guys at 18, and they often do both ears now. (For women, 2 each side is almost the default 'setting' for earrings now.) Among young male waiters, earrings are seemingly almost 'obligatory', right?
Re. tattoos, it used to be very much a man thing (military men, bikers, etc.) but now in North America even more women than men use the parlor, apparently; 59%-70% of parlor clients are female; among military personnel, an even higher proportion of females get tattoos than men do; and among military wives it's a really widespread practice, often gotten in faith, patriotic and/or family themes: on the surface a bit radical/edgy but in actual fact very much a mainstream expression of conservative values, really, it seems.