I don't know how it worked for anyone else, but I remember the selective service PSA ads when I was growing up -- (that's a manual emdash) If you don't sign up for selective service when you turn 18, you'll be celebrating your birthday at pound-me-in-the-ass federal prison. Or maybe you couldn't get a welfare check, college loan, or federal job. The details are a bit fuzzy.

Then a month or two before my 18th birthday, I got a postcard saying I had been auto-registered. It was a rather disappointing denouement.