Assuming he's talking about the US army, voluntarily joining is the only way to join. I would think that someone would join the army because they either have a desire to serve their country, or because the army will put you through school. Or both. I truly do not understand why you are ridiculing him.
As for the CLEP exams, I don't have much knowledge to share. I wouldn't expect them to be easy, though, as they cover material taught in typical college courses. Being that you haven't taken any college courses (or at least implied this in your post), I should imagine they'd be pretty difficult. The college board sells exam guides for individual tests, and from what I've heard, the stuff you'll see in those is pretty much the same that you'll see on the tests. Definitely consider buying a few of those before you take the tests. They're $10 each. The study guide they sell covers all exams they offer, and is $25.
http://www.collegeboard.com/student/tes ... /prep.html