Selective Service System

If you're going to live in the US, and plan on attending a US school, chances are good you'll have to register. You get in some big trouble if you don't register by your 26th birthday (so they give you a lot of leeway), and failing to register means you will never qualify for government aid (whether it's a loan or financial aid for school, for example).

I'd say just do it and get it over with. It's not a big boogey-man monster that's going to be creeping up on you, and you can always find a way to get out of joining the military (but you better have a good excuse and stick with it, such as being against any kind of conflict for moral/religious reasons, not just cause you don't agree with the politics surrounding the current conflict).

If you're still not convinced and are paranoid about it, just call a Veteran's Affairs office in the US. They should be able to tell you what you need to know and do.

I think males that live in countries where they're not a US state but under a US protectorate also have to register (such as those living in Guam or Puerto Rico). Sure you don't pay US taxes, but they can draft your booty too if you live there.

Jam it back in, in the dark.