Places accept different things, but you're always good with a military id or your dd-214. Some will take a picture of you in uniform.
For me, I went through all the paperwork hassle so my driver's license has my veteran status right on it. Just to make this one day a year as efficient as possible.
If you wake up at a different time, in a different place, could you wake up as a different person?
#theresafreakingghostafterus