To Military or Not to Military

I always wondered why you can go join the army at the age of 18 but you have to be 21 to buy liquor. I think that we should put a stop to that and I also think that they shouldn’t be able to draft people. How is this the “land of the free” when you can get snatched from off your living room couch and placed on a battle field? Boy do we have a way of contradicting ourselves.