How do I prove I have some Native American Blood?

The ONLY way to prove any ancestry is to research it and prove it via records, that satrs with your own birth certificate, which have your parents names on it, your parent marriage cert and/or their birth certs prove them and their parents, you can find ALL these records and lots more at home and you continue to research and prove using real records until you rach who you think/been told are the ancestors you are looking for , then you look on NA rolls, if they are meantioned then you have proved NA ancestry if not it is just another family story................ a checklist of records on here, http://familytimeline.webs.com/recordsinyourownhome.htm also on the link page at the bottom of the page are USA links and the NA rolls are on there on the link 'accessgenealogy,'

Sounds like tall tales, but the only way to prove lineage is to do standard genealogy. This requires tracing the names and established lines of descent from your ancestors. This means you have to that track down each generation using documentation.

Get tested

You are correct: they would not accept "Pop's word". DNA testing would definitely prove if you have Indian ancestry or not (it is NOT blood, but DNA. (Blood is the old notion, back when people didn't know about DNA.) No one looks Indian. Just look up Jim Thorpe or any other famous Indian. Check: http://www.ranker.com/list/the-30-hottest-women-of-native-american-descent/greg?page=3 For your purposes, DNA is not considered, you would need to follow the paper trail, which means finding your birth certificate, then the birth/marriage/death certificates of your parents, their parents, and their parents, back to your Indian ancestors. (More or less the same requirements for joining D.A.R., S.A.R., Mayflower Descendants, etc.) Of course, the same applies to your claim of German and Irish ancestry: you need to follow the paper trail. So, start digging.

you must wear Indian clothes.and join the tribe.