This is from the website: http://www.sss.gov/ (the Selective Service System)
ATTENTION, UNDOCUMENTED MALES & IMMIGRANT SERVICING GROUPS!
If you are a man ages 18 through 25 and living in the U.S., then you must register with Selective Service. It’s the law. You can register at any U.S. Post Office and do not need a social security number. When you do obtain a social security number, let Selective Service know. Provide a copy of your new social security number card; include your complete name, date of birth, Selective Service registration number, and current mailing address; and mail to the Selective Service System, P.O. Box 94636, Palatine, IL 60094-4636.
Be sure to register before your 26th birthday. After that, it’s too late!
Selective Service does not collect any information which would indicate whether or not you are undocumented. You want to protect yourself for future U.S. citizenship and other government benefits and programs by registering with Selective Service. Do it today.
(emphasis added by Cowgirl to highlight the more insane parts of this memo)